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589 Cards in this Set
- Front
- Back
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enationmers
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molecules that are mirror images of each other
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structural isomers
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diferent covalent arrangments of atoms
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geometric isomers
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different spatial arrangements of atoms
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hydroxyl
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hydrogen atom bonded to oxygen atom (alcohols)
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carbonyl
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carbon atom joined to oxygen atom
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aldehyde
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organic compound with carbonyl group at end of skeleton
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ketone
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organic compound with carbonyl group not at end of carbon skeleton
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carboxyl
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oxygen atom double bonded to carbon atom also to hydroxyl group (-COOH), called carboxylic acids or organic acids
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amino group
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-NH2
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sulfydryl group
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-SH, compounds called thiols
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phosphate group
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-PO4
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Pentose sugars (examples)
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Ribose, ribulose
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Hexose Sugars (examples)
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glucose, galactose, fructose
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Monosaccharides (examples)
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glyceraldehyde, ribose, glucose, galactose, fructose
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disaccharides (examples)
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maltose, sucrose, lactose
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glycosidic linkage
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covalent bond formed between two monosacharides by dehydration reaction
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polysaccharides (examples)
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starch, glycogen, cellulose, chitin
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fatty acid
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glycerol with long carbon skeleton
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glycerol
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alcohol with thre carbons, each bearing a hydroxyl group
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ester linkage
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C-O-C bond (i.e., between glycerol, fatty acid)
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saturated fatty acid
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no double bonds between carbon atoms in tail
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unsaturated fatty acid
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one or more double bonds (kink in shape) in tail
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phospholipids
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two fattyt acids as opposed to 3, third is to phosphate group (attached to glycerol)
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fat (triacylglycerol)
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3 fatty acids each joined to glycerol, hydrophobic because of non-polar (-H bonds in fatty acid tail)
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micelle
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phospholipid droplet with hydrophilic phosphate heads on outside
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steroids
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lipid, carbon skeleton consisting of four fused rings
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cholesterol
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steroid, component of animal cell membranes, precursor to fusion of other steroids
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amino acid
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organic compound possessing carboxyl, amino, R groups
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R group or side chain
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variable group that differs for amino acids
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peptide bond
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covalent bond between amino acids, dehydration reaction between amino, carboxyl groups
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primary structure
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unique sequence of amino acids
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secondary structure
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polypeptide chain folded/coiled in patterns - result from hydrogen bonds at regular intervals along polypeptide backbone
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alpha helix
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secondary structure, delicate coil (lysozyme)
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pleated sheet
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two regions of polypeptide chain lie parallel to each other, held together by hydrogen bonds
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tertiary structure
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irregular contortions from bonding between side chains
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hydrophobic interaction
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clustering of amino acids with hydrophobic (nonpolar) side chains cluster at core of protein, out of contact with water
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disulfide bridges
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strong covalent bonds between sulfhydryl (-SH) side chains (forms -S-S-)
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quaternary structure
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overall protein structure that results from aggregation of polypetide subunits (collagen, hemoglobin)
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chaperone proteins
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molecules that function as temporary braces in assisting the folding of other proteins
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nucleotides
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monomers of nucleic acids, contain nitrogenous base, pentose, phosphate groups
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difference between deoxyribose, ribose
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deoxyribose lacks oxygen atom on number two carbon
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phosphodiester linkages
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covalent bonds between phosphate of one nucleotide and sugar of next
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metabolism
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totality of organism's chemical processes
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catabolic pathways
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release energy by breaking down complex molecules
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anabolic pathways
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consume energy to build complicated molecules from simpler ones
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ATP
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adenine bonded to ribose with chain of three phosphates attached to ribose, hydrolysis results in ADP+P(i) + Energy
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phosphorylated intermediate
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coupling of ATP hydrolysis directly to some other molecule
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catalyst
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chemical agent that changes the rate of reaction w/o being consumed in reaction
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induced fit
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held by hydrogen and ionic bonds
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cooperativity
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interaction with one substrate molecule triggers the same favorable conformational change in all other subunits of enzyme
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resolving power
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measure of clarity of an image, minimum distance two points can be separated and still be distinguished as two separate points
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nuceloid
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region of prokaryotic cell where genetic material is concentrated
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cisterane
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network of membranous tubules and sacs in the ER
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functions of smooth ER
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synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poisons
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functions of rough ER
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synthesis of secretory proteins, secretion through transport vesicles, membrane production
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Golgi apparatus
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flattened membranous sacs (cisternae), pacakages, modifies, and organizes molecules, synthesizes some polysaccharides
cis - located near ER, receives vesicles trans - gives rise to vesicles that will be released |
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lysosome
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membrane-bounded sac of hydrolytic enzymes, low pH (5) maintained by pumping hydrogen ions from cytosol into lumen of lysosome
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autophagy
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recycling of cell's own organic material
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tonoplast
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membrane enclosing central vacuole in plant cells
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vacuole
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stores organic compounds, inorganic ions, pigments, poisons
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cristae
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convoluted infoldings of inner membrane of mitochondrion
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mitochondrial matrix
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compartment of mitochondria enclosed by inner membrane
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thylakoids
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memranous system of flattened sacs in chloroplast
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grana
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stacked thylakoids
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stroma
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fluid outside of thylakoids in chloroplasts
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peroxisome
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specialized metabolic compartment containing enzymes that transfer hydrogen from various substrates to oxygen, producing hydrogen peroxide (H2O2)
-break down fatty acids, detoxify harmful compounds -contains enzymes to convert H2O2 to H2O -present in emerging seedlings to convert fatty acids to sugar |
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cytoskeleton
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network of fibers extending through cytoplasm - motility, structure
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microtubules
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hollow, wall consists of 13 columns of tubulin molecules, largest in diameter, contains alpha-tubulin and beta-tubulin
functions - maintenance of cell shape (compression resistance), cell motility (cilia, flagella), chromosome movement in cell division, organelle movements |
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microfilaments
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two intertwined strands of actin, smallest in diameter
functions - maintenance of cell shape (tension-bearing elements), changes in cell shape, muscle contraction, cytoplasmic streaming, cell motility (pseudopodia), cell division (cleavage furrow formation) |
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intermediate filaments
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fibrous proteins supercoiled into thicker cables, maintenance of cell shape (tension-bearing elements), anchorage of nucleus and other organelles, formation of nuclear lamina
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centrosome
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region of nucleus from which microtubules grow out
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centriole
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two in each centrosome, each composed of nine sets of triplet microtubules arranged in ring
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cilia/flagella
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nine doublets of microtubules arranged in ring
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basal body
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anchors microtubule assembly in cilium or flagellum, structurally identical to centriole
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dynein
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large protein making up basal motors
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cytoplasmic streaming
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circular flow of cytoplasm within cell to speed distribution of materials within cel
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middle lamella
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thin layer rich in sticky polysaccharides (pectin), center of cell wall
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extracellular matrix
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glycoproteins (collagen, fibronectins, integrins) that support cell, also help in adhesion, movement, regulation
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plasmodesmata
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perforations in cell walls that form channels
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tight junctions
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connections that form continuous belts around cell, fusion between membranes of adjacent cells
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desmosomes (anchoring junction)
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function like rivets, fastening cells together into strong epithelial sheets, reinforced by intermediate filaments
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gap junctions (communicating junctions)
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provide cytoplasmic channels between adjacent cells
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amphipathic
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has both hydrophobic and hydrophilic regions
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integral proteins
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generally transmembrane proteins, hydrophobic regions that completely span hydrophobic interior of membrane
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peripheral proteins
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proteins not embedded in lipid bilayer
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What is the lipid bilayer permeable to?
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small, polar, uncharged molecules (water, ethanol)
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transport proteins
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transport specific ions and polar molecules
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facilitated diffusion
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diffusion facilitated with the help of transport proteins
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membrane potential
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voltage across a membrane
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electrogenic pump
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transport protein that generates membrane potential
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proton pump
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actively transports hydrogen ions out of cell
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cotransport
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when one ATP-powered pump indirectly drives the active transport of several other solutes
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ligands
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extracellular substances that bind to the receptors on proteins
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breakdown of glucose (energy)
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-686 KCal (-2870 KJ) per mole
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oxidation
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loss of electrons from substance
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reduction
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addition of electrons to a substance
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NAD+
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coenzme, oxidizing agent in cell respiration
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dehydrogenase
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enzyme that removes a pair of hydrogen atoms from the substrate
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glycolysis
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process that reaks glucose into two pyruvate molecules, source of 2 ATP, 2 NADH, 2 pyruvate, prepares molecules for further oxidation in Krebs cycle, takes place in cytoplasm
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energy-investment phase (glycolysis)
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cell spends ATP to phosphorylate fuel molecules
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energy-payoff phase
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ATP is produced by substrate phosphorylation, NAD+ is reduced to NADH
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enzymes in glycolysis
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hexokinase, phosphofructokinase - transfer phosphate group from ATP to organic sugar
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oxidative phosphorylation
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using an electron transport chain to combine hydrogen ions and molecular oxygen into water
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substrate-level phosphorylation
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enzyme transfers a phosphate group from a substance to ADP
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link reaction
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mitochondria, pyruvate ---> acetyl CoA, NAD+ -----> NADH, releases CO2
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coenzyme A
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catalyzes pyruvate ----> acetyl CoA
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Krebs Cycle
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Acetyl CoA (3-carbon) ---> citrate (six-carbon) ----> (etc) -----> oxaloacetate (4-carbon)
Products: 3 NADH (+1 from link reaction), 1 FADH2, 1 ATP (for each turn of Krebs cycle) |
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electron transport chain
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located in inner membrane of mitochondria
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cytochromes
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proteins in the electron transport chain
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ATP synthase
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enzyme that makes ATP using energy of existing ion gradient
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cell respiration (total energy)
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36-38 ATP, 7.3 kcal per mole of ATP
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alcohol fermentation (conversion)
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pyruvate-ethanol
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fermentation
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glycolysis plus reactions that regnerate NAD+, transfer electrons from NADH to pyruvate
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lactic acid fermentation
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pyruvate reduced directly by NADH to form lactate as a waste product, no release of CO2
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facultative anaerobes
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(yeasts, bacteria) can make ATP to survive in anaerobic or aerobic respiration
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catabolism of proteins
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proteins ----> amino acids ----> deamination in glycolysis-----> Krebs cycle
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catbolism of fats
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fats -----> glycerol -----> glycolysis
fatty acids ----> acetyl CoA (beta oxidation) |
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phosphofructokinase
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inhibited by citrate, ATP
stimulated by AMP |
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mesophyll
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tissue in the interior of the leaf
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light reactions
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first stage of photosynthesis
H20+Light+NADP+ + ADP+Pi ----> 02+NADPH +H+ + ATP |
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Calvin cycle
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second stage of photosynthesis (dark reaction)
CO2+NADPH+ATP ----> CH20 + NADP+ + ADP + Pi |
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NADP+
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electron acceptor for light reaction
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photophosphorylation
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generation of ATP by powering the addition of a phosphate group to ADP using light energy
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carbon fixation
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incorporation of carbon into organic compounds
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absorption spectrum
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graph plotting a pigment's light absorption versus wavelength
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action spectrum
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wavelength vs. measure of photosynthetic rate
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chlorophyll a
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blue-green, participates directly in light reactions
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chlorophyll b
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accessory pigment, absorbs light and transfers energy to chlorophyll a, yellow-green
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carotenoids
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accessory pigments, hydrocarons that are various shades of yellow and orange
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photosystem I
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P700 reaction center, best at absorbing far-red light (700 nm), electrons from photosystem II reduce NADP+ to NADPH
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photosystem II
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P680 reaction center, electrons come from H20, produces O2, photophosphorylation
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location of Calvin cycle
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stroma
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location of light reaction
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thylakoid membrane
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location of release of H+, O2
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thylakoid space
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cyclic electron flow
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produces ATP by sending electron in photosystem I back down electron transport chain
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glyceraldehyde 3-phosphate (G3P)
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carbohydrate produced directly from Calvin cycle
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carbon fixation in Calvin cycle
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CO2 ----> ribulose biphosphate (RUBP), catalyzed by rubisco
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reduction in Calvin cycle
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NADPH gives electrons to G3P
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regeneration (Calvin cycle)
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G3P ---> RuBP
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output of Calvin cycle
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1 G3P, which goes to glucose and other organic compounds, NADP+
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C3 plants
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first organic product of carbon fixation is a 3-carbon compound (rice, wheat, soybeans)
produce less food when stomata close on hot, dry days rubisco can accept O2 in place of CO2 |
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photorespiration
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process of rubisco accepting O2
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C4 plants
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carbon fixation forms four-carbon compound (sugarcane, corn)
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bundle-sheath cells
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(C4 plants), tightly-packed sheets around veins of leaf
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mesophyll cells
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(C4 plants) - loosely arranged between bundle sheath, leaf surface
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PEP Carboxylase
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in C4 plants, adds CO2 to PEP - higher affinity than rubisco, can fix CO2 efficiently when CO2 levels are low (stomata are partially closed)
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CAM plants
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crassulacean acid metabolism (succulent plants)
organic acids made in night provide CO2 in day when stomata are closed |
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sister chromatids
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identical copies of chromosome's DNA molecule in duplicated chromosome, intially attached along lengths
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centromere
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narrow "waist" at specialized region of chromosome
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interphase
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90% of mitotic cycle, cell growth, chromosomes copied
G1 phase, S phase, G2 phase |
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G1 Phase
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interphase, cell growth
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S phase
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interphase (synthesis), duplication of chromosomes
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G2 Phase
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interphase, growth and preparation for cell division
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mitotic spindle
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fibers made of microtubules, associated proteins, begins to form in cytoplasm during prophase (protein tubulin)
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centrosome
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microtubule organizing center, has two centrioles in center (animal cells), replicates during interphase, separate in prophase, prometaphase
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kinetochore
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structure of proteins and specific sections of chromosomal DNA at centromere, located in each chromatid
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prophase
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more tightly coiled chromatin fibers - condense to discrete chromosomes
nucleoli disappear, sister chromatids form mitotic spindle beings to form, microtubules radiate from two centrosomes, centrosomes move away from each other |
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prometaphase
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fragmentation of nuclear envelope, microtubules interact with condensed chromosomes, microtubules extend from each pole toward middle of cell
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metaphase
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chromosomes convene on metaphase plate (plane equidistant between spindle's two poles), centrosomes at opposite poles of cell
centromeres alligned microtubules attached to kinetochores |
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anaphase
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paired centromeres separate, sister chromatids move to opposite corners of cell
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telophase
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daughter nuclei form at two poles of cell, nuclear envelopes arise out of parent cell's nuclear envelope, chromatin becomes more loosely coild
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cytokinesis
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division of cytoplasm, hastened by actin, myosin
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cleavage furrow
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shallow groove in cell surface near old metaphase plate, right before cytokinesis
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cell plate
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cytokinesis in plant cells, produced by vesicles derived from Golgi apparatus that move along microtubules to the center of the cell
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binary fission
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cell division in prokaryotes, circular chromosome is replicated, move to opposite corners, then cytokinesis
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cyclin-dependent protein kinases
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signals for cell division to continue at checkpoints
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cyclin
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protein that activates kinase by attaching to it
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MPF
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CDK complex that triggers mitotic stage in cells
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growth factor
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protein relased by certain body cells that stimulates other cells to divide
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cancer cells
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no density-dependent nor anchorage-dependent division
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locus
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a gene's specific location along the length of a chromosome
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homologous chromosomes
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the chromosomes that move up a pair, each carrying genes controlling the same inherited characters
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autosome
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chromosomes other than sex chromosomes
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haploid
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cell with a single chromosome set
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syngamy
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fertilization of gametes
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zygote
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fertilized egg
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Interphase I
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same as mitosis interphase
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Prophase I
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chromosomes condense, synapsis, other cellular components - same as mitosis
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synapsis
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prophase I of meiosis, homologous chromosomes come together as pairs - forms tetrads
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chiasmata
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crossings of homologous chromosomes that hold them together
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metaphase I
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same as mitosis metaphase
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anaphase I
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sister chromatids remain attached at centromeres, move as single unit to same poles
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telophase I/cytokinesis
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cells become haploid
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prophase II
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spindle apparatus forms
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metaphase II,etc
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results in four haploid daughter cells
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sexual variation
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independent assortment of chromosomes, crossing over, random fertilization
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crossing over
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occurs in prophase of meiosis I, genetic exchanges occur at chiasmata
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random fertilization
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i.e., different possible sperm
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incomplete dominance
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the F1 hybrids have an appearance somewhere in between the phenotypes of the two parental varieties
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codominance
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both alleles are separately manifest in the phenotype (blood type)
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pleiotropy
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ability of a gene to affect an organism in many ways
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epistasis
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a gene at one locus alters the phenotypic expression of a gene at another locus
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cystic fibrosis
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defection chloride channels causes thicker mucus
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Tay-Sachs disease
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recessive allele - dysfunctional enzyme that gails to break down brain lipids - Ashkenazie Jews
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sickle-cell anemia
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substitution of amino acid in hemoglobin protein of red blood cells
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Huntington's disease
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dominantly inherited, degenerative disease of nervous system, affects individuals at 35-45 years of age
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amniocentesis
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14th-16th week of pregnancy, amniotic fluid withdrawn from uterus
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chorionic villus sampling (CVS)
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suctions off small amount of featl tissue from the placenta, occurs in 8th to 10th week of pregnancy
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sex-linked genes
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genes located on a sex chromosomes
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linked genes
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genes located on the same chromosome tend to be inherited together in genetic crosses because the chromosome is passed along as a unit
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recombinants
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offspring that have different genotypes than the parents
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Barr body
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inactive X in each cell of a female condenses into a compact object
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nondisjunction
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members of a pair of homologous chromosomes do not move apart properly during meiosis I or in which sister chromatids fail to separate during meiosis II
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aneuploidy
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abnormal chromosome number resulting when either of the aberrant gametes unites with a normal one at fertilization (nondisjunction)
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monosomic
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gamete missing a chromosome
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polyploidy
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chromosomal alteration in which an organism as more than two complete chromosome sets
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deletion
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chromosomal fragment lacking a centromere is lost during cell division
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inversion
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deleted chromosome reattached in reverse orientation
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translocation
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fragment joins nonhomologous chromosome
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Klinefelter's syndrome
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XXY (male) - sterile, abnormally small testes
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Jacobson's syndrome
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XYY, taller, aggressive
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XXX
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cannot be distinguished from XX females except by karyotype
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Turner's syndrome
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XO, no maturation of sex organs, no secondary sex characteristics, sterile, short
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genomic imprinting
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certain gnes imprinted in each generation depending on whether gene resides in female or male
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fragile X syndrome
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abnormal X chromosome, tip hangs onto rest of chromosomes by a thin thread of DNA
mental retardation - caused by maternal imprinting |
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Frederic Griffith
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1928, medical officer studied Streptococcus pneumonia bacteria, discovered transformation (heated pathogenic bacteria, mixed dead remains with live harmless ones, found that harmless ones adopted HERITABLE pathogenic trait)
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transformation
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a change in genotype and phenotype due to the assimilation of external DNA by a cell
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Oswald Avery
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along with McCarty and MacLeod, announced that transforming agent was DNA (1944)
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bacteriophages
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viruses that infect bacteria
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Hershey and Chase
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1952, discovered that T2 (E Coli phade) could infect E Coil and then could make cell make T2 phages
used radioactiv eisotopes to tag DNA, protein concluded that DNA of virus is injected into host cell, while proteins remain outside - causes production of new viral DNA and proteins |
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Erwin Chargaff
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1947, found that nitrogenous bases are present in characteristic ratio in all organisms
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James Watson and Francis Crick
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1950's, determined that DNA structure was double helix, model explaied Chargaff's rule
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semiconservative model of replication
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two strands of parental molecule separate, each functions as a template for synthesis of a new complementary strands
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Meselson, Stahl
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1950s, tested three alternative hypotheses for DNA regulation
cultured E coli with nitrogen isotope, tracked resulting DNA, supported semiconservative model |
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origins of replication
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sites of beginning of DNA replication
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replication fork
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Y-shaped region where new strands of DNA are elongating
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DNA polymerases
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catalyze elongation of DNA, add nucleotides to new DNA strands
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leading strand
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the new continuous complementary DNA strand synthesized along the template strand in the mandatory 5'-->3' direction
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lagging strand
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a discontinuously synthesized DNA strand that elongates in a direction away from the replication fork
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Okazaki fragments
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pieces of lagging strand that are syntheized each in 5' ---> 3' direction but overall in 3' --> 5' direction
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DNA ligase
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joins Okazaki fragments of lagging strand into a single strand
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primer
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original preexisting chain in DNA replication, RNA, converted to DNA before ligase
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primase
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enzyme that joins RNA nucleotides to make primer (10 nucleotides long)
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helicase
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enzyme that untwists the double helix at the replication fork
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single-stranded binding protein
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hold DNA strands apart while they serve as templates for complementary strands
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mismatch repair
|
enzyme that fixes mistakes when DNA is copied
|
|
|
nuclease
|
DNA-cutting enzyme
|
|
|
excision repair
|
DNA repair involving nuclease, repair synthesis
|
|
|
telomeres
|
nucleotide sequences at end of strand - repetitions of short nucleotide sequences, prevent ends from activating cell's systems for monitoring DNA damage
|
|
|
telomerase
|
enzyme that catalyzes the lengthening of telomeres, contains RNA molecule that seves as template for new telomere segments
|
|
|
auxotrophs
|
mutants that cannot survive on minimal medium because they are unable to synthesize certain essential molecules from the minimal ingredients
|
|
|
Beadle, Tatum
|
one gene-one polypeptide hypothesis
|
|
|
transcription
|
the synthesis of RNA under the direction of DNA
|
|
|
messenger RNA
|
transcript of gene's protein-building instructions
|
|
|
translation
|
actual synthesis of a polypeptide, occurs under direction of mRNA
|
|
|
RNA processing
|
yields finished mRNA after transcription
|
|
|
primary transcript
|
initial RNA transcript
|
|
|
template strand
|
transcribed DNA strand that provides the template for ordering the sequence of nucleotides in an RNA transcript
|
|
|
codons
|
mRNA base triplets
|
|
|
degenerative genetic code
|
more than one codon translates to single amino acid
|
|
|
RNA polymerase
|
enzyme that pries the two strands of DNA apart and hooks together the RNA nucleotides as they base-pair along the DNA template
|
|
|
transcription unit
|
stretch of DNA that is transcribed into an RNA molecule
|
|
|
promoter
|
region od DNA where RNA polymerase attaches and initiates transcription
|
|
|
transcription factors
|
collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription
|
|
|
transcription initiation complex
|
completed assembly of transcription factors and RNA polymerase bound to the promoter
|
|
|
TATA box
|
crucial promoter DNA sequence
|
|
|
terminator
|
DNA sequence that stops transcription
|
|
|
alteration of mRNA
|
5' cap of modified guanine - protects mRNA from degradation by hydrolytic enzymes, also sign for ribosomes to attach during translation
3' end - poly(A) tail (30-200 adenine nucleotides) - inhibits RNA degradation, facilitates export of mRNA from nucleus |
|
|
RNA splicing
|
removal of large portion of RNA molecule
|
|
|
introns
|
noncoding segments of nucleic acid that lie beween coding regions
|
|
|
exons
|
other regions of nucleic acids that are eventually expressed
|
|
|
spliceosome
|
a complex assembly that interacts with the ends of an RNA intron in splicing RNA; reases an intron and joins the two adjacent exons
|
|
|
ribozymes
|
RNA molecules that function as enzymes
|
|
|
domains
|
modular architecture of proteins consisting of discrete structural and functional components
|
|
|
transfer RNA
|
an RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing appropriate codons in the mRNA
|
|
|
anticodon
|
nucleotide triplet which binds to complementary codon on mRNA
|
|
|
wobble
|
relaxation of base-pairing rules in translation allowing for tRNA versatility
|
|
|
amnioacyl-tRNA synthetase
|
specific enzyme that joins amino acid to correct tRNA
|
|
|
ribosomal RNA
|
proteins and RNA molecules that make up ribosomal subunits in translation
|
|
|
P site
|
holds tRNA carrying the growing polypeptide chain
|
|
|
A site
|
holds tRNA carrying the next amino acid to be added to the chain
|
|
|
E site
|
exit site
|
|
|
elongation
|
codon recognition, peptide bond formation, translocation
|
|
|
termination
|
release factor binds to stop codon in A site, does not move to E site
|
|
|
polyribosomes
|
strings of ribosomes that are attached to one messenger RNA molecule
|
|
|
signal peptide
|
polypeptides or proteins destined for the endomembrane system or for secretion
|
|
|
mutations
|
changes in genetic material of a cell (or virus)
|
|
|
point mutations
|
chemical changes in just one or few base pairs in a single gene
|
|
|
base-pair substitution
|
replacement of one nucleotide and its partner in the complementary DNA strand
|
|
|
missense mutations
|
altered codon still codes for an amino acid
|
|
|
nonsense mutations
|
alterations that change an amino acid codon to a stop codon
|
|
|
frameshift mutation
|
insertion or deletion of a nucleotide
|
|
|
capsid
|
protein shell that encloses the viral genome
|
|
|
viral envelopes
|
membranes in some viruses that cloak the capsid
|
|
|
host range
|
limited range of host cells that each type of virus can infect
|
|
|
lytic cycle
|
viral reproductive cycle that culminates in death of the host cell
|
|
|
virulent virus
|
virus thta only reproduces through a lytic cycle
|
|
|
lysogenic cycle
|
replicates the viral genome without destroying the host
|
|
|
temperate viruses
|
viruses that are capable of using both modes of reproducing within a bacterium
|
|
|
prophage
|
a phage genome that has been inserted into a specific site on the bacterial chromosome
|
|
|
provirus
|
viral DNA that inserts into a host genome
|
|
|
retrovirus
|
RNA virus that has genetic information which flows the reverse way
|
|
|
reverse transcriptase
|
enzyme that transcribes DNA from an RNA template
|
|
|
vaccines
|
harmless variants or derivatives of pathogenic microbes that stimulate the immune system to mount defenses against the actual pathogen
|
|
|
horizontal transmission
|
plant is infected from an external source of the virus
|
|
|
vertical transmission
|
a plant inherits a viral infection from a parent
|
|
|
viroids
|
tiny molecules of naked circular RNA that infect plants
|
|
|
prions
|
infectious proteins
|
|
|
nucleoid
|
dense region of DNA in bacteria
|
|
|
transduction
|
phages carry bacterial genes from one host cell to another
|
|
|
generalized transduction
|
bacterial DNA fragment is packaged in a phage capsid after host DNA is hydrolyzed, transducing phage infects new host cells, where recombination occurs
|
|
|
specialized transduction
|
lysogenic cycle, genome of phage integrates into host bacterium's chromosome at specific site
when phage is excised from chromosome, takes small region of bacterial DNA adjacent to the prophage, injects bacterial genes along with the phage's genome |
|
|
conjugation
|
direct transfer of genetic material between two bacterial cells that are temporarily joined, sex pili attach from male to female, cytoplasmic bridge forms
|
|
|
F factor
|
special piece of DNA that allows formation of sex pili
|
|
|
plasmid
|
small, circular, self-replicating DNA molecule separate from the bacterial chromosome
|
|
|
episome
|
genetic element that can replicate either as a plasmid or as part of the bacterial chromosome
|
|
|
F plasmid
|
25 genes, most required for the production of sex pili
|
|
|
Hfr cell
|
high frequency of recombination, has F factor built into chromosome
|
|
|
R plasmids
|
plasmids that carry genes conferring resistance
|
|
|
transposon
|
transposable genetic element, piece of DNa that can move from one location to another in a cell's genome
responsible for bringing multiple genes for antibiotic resistance into a single R plasmid by moving genes to that location from different plasmids |
|
|
insertion sequences
|
simplest bacterial transposons, consist of only DNA necessary for act of transposition
|
|
|
inverted repeats
|
noncoding DNA sequences about 20-40 nucleotides long that bracket transposable genes
|
|
|
direct repeats
|
DNA sequences that flank a transposon in its new site
|
|
|
composite transposon
|
transposons longer and more complex than insertion sequences
|
|
|
operator
|
segment of DNA that acts as a switch for gene expression for certain enzymes
|
|
|
operon
|
the entire stretch of DNA required for enzyme production for the tryptophan pathway (operator, promoter, genes controlled)
|
|
|
repressor
|
protein that binds to operator, switching off operon
|
|
|
regulatory gene
|
gene that codes for repressor protein
|
|
|
corepressor
|
small molecule that cooperates with a repressor protein to switch an operon off
|
|
|
B-galactosidase
|
enztme that catalyzes hydrolysis of lactose into glucose and galactose
|
|
|
inducer
|
a specific small molecule that inactivates repressor
|
|
|
cyclic AMP (cAMP)
|
accumulates when glucose is absent
|
|
|
cAMP receptor protein (CRP)
|
regulatory protein, activator of transcription
|
|
|
nucleosome
|
the basic, beadlike unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone
|
|
|
histone
|
a small protein with a high proportion of positively charged amino acids that binds to the negatively-charged DNA and plays a key role in its chromatin structure
|
|
|
heterochromatin
|
highly-condensed interphase chromatin
|
|
|
euchromatin
|
less compacted interphase chromatin
|
|
|
repetitive DNA
|
nucleotide sequences that are present in many copies in a genome, noncoding, usually not within a gene
|
|
|
gene amplification
|
selective replication of certain genes (egg cell making enormous number of ribosomes)
|
|
|
retro transposons
|
transposable elements that move within a genome by means of an RNA intermediate
|
|
|
control elements
|
segments of noncoding DNA that help regulate transcription of a gene by binding proteins
|
|
|
oncogenes
|
cancer-causing cells
|
|
|
protooncogenes
|
code for proteins that stimulate normal cell growth and division
|
|
|
tumor-suppressor genes
|
genes whose normal products inhibit cell division
|
|
|
ras gene
|
codes for Ras, a G protein that relays a growth signal from a growth-factor receptor on the plasma membrane to a cascade of protein kinases
|
|
|
p53 gene
|
expression triggered by damage to a cell's DNA, activates other genes to halt cell cylce, activate DNA repair, or cause apoptosis (programmed cell death)
|
|
|
biotechnology
|
manipulation of organisms or their components to perform practical tasks or provide useful products
|
|
|
gene cloning
|
developing multiple identical copies of DNA
|
|
|
restriction enzymes
|
enzymes that cut DNA molecules at a limited number of specific locations
|
|
|
restriction site
|
recognition sequence for a particular restriction enzyme
|
|
|
restriction fragments
|
pieces of DNA that result from exposure to restriction enzymes
|
|
|
sticky end
|
single-stranded end of restriction fragment that form hydrogen-bonded base pairs with complementary single-stranded stretches on other DNA molecules cut with same enzyme
|
|
|
cloning vector
|
original plasmid before exposure to restriction enzyme, DNA ligase
|
|
|
nucleic acid hybridization
|
process of detecting gene, depends on base pairing between gene and complementary sequence (nucleic acid probe)
|
|
|
expression vector
|
cloning vector that contains the requisite prokaryote promoter just upstream of a restriction site where the eukaryotic gene can be inserted
|
|
|
complementary DNA (cDNA)
|
artificial eukaryotic DNA without introns
|
|
|
electroporation
|
brief electrical pulse applied to solution containing cells in order to make transformation more efficient
|
|
|
PCR
|
polymerase chain reaction, technique by which any piece of DNA can be quickly amplified without using cells
heat-resistant DNA polymerase, primers (to initiate DNA synthesis at selected site), nucleotides heat (separates DNA strands) --> cooled to allow primers to bind to target sequence --> DNA polymerase adds nucleotides to 3' ends of primers |
|
|
gel electrophoresis
|
the separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel
|
|
|
Southern blotting
|
a hybridization technique that enables researchers to determine the presence of certain nucleotide sequences in a sample of DNA
|
|
|
restriction fragment length polymorphisms (RFLPs)
|
differences in DNA sequence of homologous chromosomes that result in different restriction fragment patterns, useful as genetic markers for making linkage maps
|
|
|
in situ hybridization
|
using a nucleic acid probe to find the general location of a gene on a eukaryotic chromosome
|
|
|
antisense nucleic acid
|
single-stranded molecules of DNA or RNA that have been constructed explicitly to base-pair with mRNA molcules and block their translation
|
|
|
transgenic organisms
|
organisms that contain genes from another species
|
|
|
biogeography
|
the geographical distribution of species - island in close proximity have similar but often indigenous species (evidence for evolution)
|
|
|
homologous structures
|
structures in different species that are similar because of common ancestry
|
|
|
gene pool
|
total aggregate of genes in a population at any time
|
|
|
genetic structure
|
population's frequencies of alleles and genotypes
|
|
|
Hardy-Weinberg Theorem
|
the frequencies of alleles and genotypes in a population's gene pool remain constant over the generations unless acted upon by agents other than sexual recombination
p^2+2pq+q^2 = 1 p^2=frequence of AA 2pq = frequency of Aa + frequency of aA q^2=frequency of aa |
|
|
microevolution
|
a generation-to-generation change in a population's allele or genotype frequencies
|
|
|
genetic drift
|
changes in the gene pool of a small population due to chance
|
|
|
bottleneck efect
|
genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population
|
|
|
founder effect
|
a cause of genetic drift attributed to colonization by a limited number of individuals from a parent population
|
|
|
gene flow
|
genetic exchange due to the migration of fertile individuals or gametes between populations
|
|
|
nonrandom mating
|
inbreeding (mating between closel-related partners), assortative mating
|
|
|
assortative mating
|
individuals select partners that are like themselves in certain phenotypic characters
|
|
|
polymorphism
|
the coexistence of two or moe distinct forms of individuals (polymorphic characters) in the same population
|
|
|
geographical variation
|
differences in genetic structure between populations
|
|
|
cline
|
graded change in some trait along a geographic axis
|
|
|
balanced polymorphism
|
the ability of natural selection to maintain diversity in a population -i.e. heterozygote advantage, hybrid vigor, frequency-dependet selection
|
|
|
hybrid vigor
|
when cross breeding between two different varieties produces stroner hybrids than either parent
due to segregation of recessive allels, heteozygote advantage |
|
|
frequency-dependent selection
|
the reproductive success of any morph declines if that phenotype form becomes too common in the population
|
|
|
neutral variation
|
genetic variations that are trivial in their impact on reproductive success
|
|
|
Darwinian fitness
|
the relative contribution an individual makes to the gene pool of the next generation
|
|
|
relative fitness
|
the contribution of a genotype to the next generation compared to the contributions of alternative genotypes for the same locus
|
|
|
stabilizing selection
|
acts against extreme phenotypes and favors the more common intermediate variants
|
|
|
directional selection
|
shifting the frequency curve for variations in some phenotypic character in one direction or the other by favoring what are initially relatively rare individuals that deviate from the average for that character
|
|
|
diversifying selection
|
environmental conditions are varied in a way that favors individuals on both extremes of a phenotypic range over intermediate phenotypes - can result in balanced polymorphism
|
|
|
sexual dimorphism
|
distinction between the secondary sex characteristics of sexual dimorphism
|
|
|
sexual selection
|
selection based on variation in secondary sex characteristics, leading to the enhancement of sexual dimorphism
|
|
|
macroevolution
|
the origin of new taxonomic groups
|
|
|
anagesis (phyletic evolution)
|
the accumulation of changes associated with the transformation of one species into another
|
|
|
cladogenesis (branching evolution)
|
budding of one or more new species from a parent species that continues to exist
|
|
|
reproductive barriers (list)
|
habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation, reduced hybrid viability, reduced hybrid fertility, hybrid breakdown
|
|
|
allopatric speciation
|
a geographical barrier that physically isolates population's initially blocks gene flow
|
|
|
allopatric speciation
|
a geographical barrier that physically isolates populations; initially blocks gene flow
|
|
|
sympatric speciation
|
intrinsic factors (chromosomal changes, nonrandom mating) alter gene flow
|
|
|
adaptive radiation
|
evolution of many diversely adapted species from a common ancestor (island chain example)
|
|
|
autopolyploid
|
(plants), an individual that has more than two chromosome sets, all derived from a single species, can cause sympatric speciation
|
|
|
allopolyploid
|
contribution of two different species to a polyploid hybrid
|
|
|
punctuated equilibrium
|
species diverge in spurts of relatively rapid change instead of slowly and gradually
|
|
|
exaptation
|
a structure that evolved in one context and became co-opted for another function (lightweight bones predate flight)
|
|
|
allometric growth
|
a difference in the relative rates of growth of various parts of the body
|
|
|
phylogeny
|
the evolutionary history of a species or a group of related species
|
|
|
analogy
|
the similarity of structure between two species that are not closely related; attributable to convergent evolution
|
|
|
convergent evolution
|
the independent development of similarity between species as a result of their having similar ecological roles and selection pressures
|
|
|
DNA-DNA hybridization
|
measuring the extent of hydrogen bonding between single-stranded DNA obtained from two sources
|
|
|
DNA sequence analyisis
|
comparing the actual nucleotide sequences of DNA segments between two samples
|
|
|
stromatolites
|
banded domes of sedimentary rock that are strikingly similar to layered mats formed today in salt marshes and some warm-ocean lagoons by colonies of bacteria and cyanobacteria
|
|
|
protobionts
|
aggregates of abiotically produced molecules
|
|
|
peptidoglycan
|
modified sugars corss-linked by short polypeptides that vary from species to species - major component of bacterial cell walls
|
|
|
Gram-positive/negative
|
presence of peptidoglycan, bacteria that are gram-negative (no peptidoglycan) are more threatening because they are more resistant to antibiotics and are often toxic
|
|
|
penicillin
|
inhibits synthesis of cross-links in peptidoglycan and prevents the formation of a functional wall
|
|
|
capsule
|
protective layer around the outside of the prokaryotic cell
|
|
|
taxis
|
movement toward or away from a stimulus
|
|
|
endospores
|
thick-coated, resistant cells procued within a bacterial cell exposed to harsh conditions
|
|
|
photoautotrophs
|
photosynthetic organisms that harness light energy to drive the synthesis of organic compounds from carbon dioxide
|
|
|
chemoautotrophs
|
need only CO2 as a carbon source, obtain energy by oxidizing inorganic substances
|
|
|
photoheterotrophs
|
use light to generate ATP but must obtain their carbon in organic form
|
|
|
chemoheterotrophs
|
must consume organic molecules for both energy and carbon
|
|
|
saprobes
|
decomposers that absorb their nutrients from dead organic matter
|
|
|
nitrogen fixation
|
prokaryotes convert N2 to NH3
|
|
|
nitrification
|
bacteria oxidize ammonium to nitrite (NO2-) and then to nitrate (NO3-)
|
|
|
denitrification
|
nitrate converted back to N2 by prokaryotes
|
|
|
ammonification
|
decomposition of organic nitrogen back to ammonium
|
|
|
faultative anaerobes
|
will use O2 if it is present but can also grow by fermentation in an anaerobic environment
|
|
|
Bacteria vs. Archaea
|
Bacteria: peptidoglycan in cell wall, unbranched hydrocarbon membrane lipids, one kind of RNA polymerase, no introns, inhibited growth in respone to antibiotics
Archaea - no peptidoglycan in cell wall, branched hydrocarbon membrane lipids, several kinds of RNA polymerase, some introns, growth not inhibited by antiobiotics |
|
|
methanogens
|
archaea, H2 is used to reduce CO2 to methane (CH4), strict anaerobes
|
|
|
extreme halophiles
|
archaea, live in extremely saline environments
|
|
|
extreme thermophiles
|
archaea, thrive in hot environments
|
|
|
opportunistic
|
pathogens that cause illness when the host's defenses are weakened
|
|
|
exotoxins
|
proteins secreted by prokaryotes (i.e., botulism)
|
|
|
endotoxins
|
components of the outer membranes of certain gram-negative bacteria (Salmonella)
|
|
|
protists
|
eukaryotic, generally unicellular (protozoa (ingestive), fungus-like (absorptive), algae (photosynthetic))
|
|
|
protist examples
|
phytoplankton, flagellates (dinoflagellates), ciliates, pseudopods (amoebas), slime molds, diatoms, water molds/mildews
|
|
|
serial endosymbiosis
|
hypothesis that mitochondria and chloroplasts were formerly small prokaryotes living within larger cells
Support: existence of endosymbiotic relationships; similarity between size of prokaryotes, chloroplasts, and mitochondria; inner membranes are similar (enzymes, transport systems); both have circular DNA and ribosomes; similar base sequences (more similar to prokaryotes than to eukaryotes) |
|
|
lichens
|
mutualistic collectives of green algae and fungi
|
|
|
oogamy
|
flagellated sperm fertilizing a nonmotile egg
|
|
|
lignin
|
the substance that hardens the cell walls of "wood" tissues in plants
|
|
|
gametangia
|
in plants, organs having protective jackets of sterile cells that prevent the delicate gametes from drying out during their development
|
|
|
vascular tissue
|
cells joined into tubes that ransport water and nutrients throughout the plant body
|
|
|
bryophyes
|
the mosses, liverworts, and hornworts; a group of nonvascular plants that inhabit the land but lack many of the terrestrail adaptations of vascular plants
gametophyte is the dominant generation no lignin, therefore short need water to reproduce, flagellated sperm spores |
|
|
antheridium
|
male gametangium
|
|
|
archegonium
|
female gametangium
|
|
|
sporangium
|
a capsule in fungi and plants in which meiosis occurs and haploid spores develop
|
|
|
xylem
|
the tube-shaped, nonliving portions of the vascualr system in plants that carries water and minerals from the roots to the rest of the plant
|
|
|
phloem
|
the portion of the vascular system in plants consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plant
|
|
|
homosporous
|
create single type of spore which develops into bisexual gametophyte (most ferns)
|
|
|
heterosporous
|
plants that produce two kinds of spores (megaspores=female gametophytes, microspores=male gametophyes)
|
|
|
seedless vascular plants (i.e. filicinophytes)
|
still require flagellated sperm, use spores to reproduce
sporophyte is dominant generation includes ferns, lycophytes, horsetails |
|
|
epiphytes
|
plants that use another organism as a substratum but are not parasites
|
|
|
seed
|
a sporophyte embryo packaged along with a food supply within a protective coat
|
|
|
nucellus
|
solid, fleshy structure - megasporangium in seed plants
|
|
|
integuments
|
additional layers of sporophyte tissues that envelop the megasporangium in seed plants
|
|
|
ovule
|
entire structure of integuments, nucellus, megaspores
|
|
|
microsopores in seed plants
|
pollen, which elongates tube to discharge sperm within the ovule, sperm generally lack flagella
|
|
|
gymnosperm
|
a vascular plant that bears naked seeds not enclosed in any specialized chambers
|
|
|
conifer
|
gymnosperm with cone that is cluster of scale-like sporophylls, generally have tracheids
|
|
|
angiosperm
|
a flowering plant, which forms seeds inside a protective chamber called an ovary, generally have vessel elements
|
|
|
micropyle
|
opening between integuments in gymnosperms
|
|
|
fiber
|
cell that reinforces xylem in angiosperms, also evolved from tracheid
|
|
|
flower
|
reproductive structure of angiosperm
|
|
|
sepals
|
a whorl of modified leaves in angiosperms that encloses and protects the flower bud before it opens
|
|
|
petals
|
brightly-colored, help attract insects in angiosperms
|
|
|
stamen
|
pollen-producing male reproductive organ of a flower, consisting of an anther and a filament
|
|
|
carpel
|
the female reproductive organ of a flower, consisting of the stigma, style, and ovary
|
|
|
filament
|
stalk in the stamen (male)
|
|
|
anther
|
where pollen is produced, terminal sac in stamen
|
|
|
stigma
|
sticky tip of carpel that receives pollen
|
|
|
style
|
similar to filament, stalk of carpel (female)
|
|
|
ovary (flower)
|
portion of a carpel in which the egg-containing ovules develop
|
|
|
fruit
|
mature ovary
|
|
|
pollen grains
|
immature male gametophyte, develops within anthers of stamen
|
|
|
ovules
|
develop in ovary, contain female gametophyte
|
|
|
embryo sac
|
female gametophyte, consists of only a few cells
|
|
|
double fertilization
|
both sperm nuclei of angiosperm pollen fertilize cells in the embryo sac
|
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cotyledons
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the one (monocot) or two (dicot) seed leaves of an angiosperm embryo
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endosperm
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a nutrient-rich tissue formed by the union of a sperm cell with two polar nuclei during double fertilization, which provides nourishment to the developing embryo in angiosperm seeds
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coevolution
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mutual evolutionary influence between two species
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fungi
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mostly multicellula, eukaryotic, heterotrophic (absorption), either sexual or asexual reproduction
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hyphae
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minute threads composed of tubular walls surrounding plasma membranes and cytoplasm
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mycelium
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interwoven mat of hyphae
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septa
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cross-walls that divide hyphae into cells, large pores to allow ribosomes, mitochondria, nuclei to flow from cell to cell
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chitin
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strong but flexible nitrogen-containing polysaccharide
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coenocytic
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referring to a multinucleated condition resulting from the repeated division of nuclei without cytoplasmic division
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haustoria
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in parasitic fungi, nutrient-absorbing hyphal tips that penetrate the tissues of the host
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fungal sexual reproduction
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plasmogamy (fusion of cytoplasm), karyogamy (fusion of nuclei), dikaryon (two nuclei)
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mycorrhizae
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mutualistic associations of plant roots and fungi
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parthenogenesis
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a type of reproduction in which females produce offspring from unfertilized eggs
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notochord
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longitudinal, flexible rod located between the digestive tube and the nerve cord
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amniotic egg
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shelled, water-retaining
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monocots
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single cotyledon, parallel veins, complexly-arranged vascular bundles, fibrous root systems, floral parts=multiples of 3
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dicots
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two cotyledons, netlike veins, vascular bundles=ring, taproot, four or five floral parts
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xylem
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vascular tissue that conveys water and dissolved minerals upward from roots into the shoots
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phloem
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vascular tissue which transports food made in mature leaves to the roots and to parts of the shoot system
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root absorption
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root hairs, mycorrhizae
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adventitious
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any plant part that grows in an unusual location
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internodes
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stem segments between nodes
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axillary bud
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potential to form branch shoot, in angle formed by each leaf and the stem
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nodes
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points at which leaves are attached
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terminal bud
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bud at apex of shoot
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apical dominance
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presence of terminal bud inhibits growth of axillary bud
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petiole
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stalk of leaf that joints it to node of stem
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parenchyma cells
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relatively unspecialized; thin, flexible primary walls
metabolic functions=task |
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collenchyma cells
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thicker primary walls, grouped in strands of cylinders
-support without restraining growth (no secondary walls or lignin) |
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sclerenchyma cells
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thick secondary walls fortified by lignin
do not elongate, rigid, may be dead function in support, consist of fibers (long, slender, tapered) and sclereids (shorter, i.e. nutshells) |
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tracheids
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dead at functional maturity, secondary walls, spiral/ring pattern
long, thin cells, tapered, also function in support, water moves primarily through pits |
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pits
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thinner regions of tracheids and vessel elements where only primary walls are present
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vessel elements
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water-conducting cells of xylem; wider, shorter, thinner-walled, less tapered
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sieve-tube members
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chains of cells that transport sucrose, other organnic compounds, and some mineral ions through phloem
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sieve plates
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end walls between sieve-tube members
pores that facilitate the flow of fluid from cell to cell along the sieve tube |
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companion cell
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connected to sieve-tube member by plasmodesmata
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perennials
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plants that live many years
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meristems
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perpetually embryonic tissues
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primary growth
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elongation at apical meristem
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secondary growth
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progressive thickening of the roots and shoots formed earlier by primary growth (occurs in gymnosperms, most dicots, but few monocots)
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root cap
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protects delicate root meristem during elongation
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quiescent center
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a region located within the zone of cell division in plant roots, containing meristematic cells that divide very slowly
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protoderm
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the outermost primary meristem, which gives rise to the epidermis of roots and shoots
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procambium
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a primary meristem of roots and shoots that forms the vascular system
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ground meristem
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a primary meristem that gives rise to ground tissue in plants
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stele
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vascular bundle of both xylem and phloem, results from procambium
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pith
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central core of parenchyma cells in stele of monocot roots
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cortex
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ground tissue (parenchyma cells) in roots (between stele and epidermis)
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endodermis
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innermost layer of cortex, cylinder one cell thick that forms the boundary between the cortex and the stele
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pericycle
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outermost layer of stele
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vascular bundle
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several strands of vascular tissue that run length of stem
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guard cells
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epidermal cells that flank stomata
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stomata
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microscopic pores surrounded by guard cells in the epidermis of leaves and stems that allow gas exchange between the environment and the interior of the plant
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transpiration
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the evaporative loss of water from a plant
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mesophyll
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ground tissue of a leaf, sandwiched between upper and lower epidermis, consists of parenchyma cells with chloroplasts, specialized for photosynthesis
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upper mesophyll
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palisade parenchyma (columnar cells)
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lower mesophyll
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spongy parenchyma (labyrinth of air spaces through which carbon dioxide and oxygen circulate around irregularly shaped cells)
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phase changes
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apical meristem changes from one developmental phase to another
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secondary plant body
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tissues produced in secondary growth
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vascular cambium
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in secondary growth, produces secondary xylem (to the interior) and phloem (to the exterior)
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cork cambium
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produces a tough, thick covering for stems and roots that replaces the epidermis, produces cork cells externally
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ray initials
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cambium cells that produce radial files of parenchyma cells (xylem, phloem rays)
radial transport of water, nutrients storage of starch, other reserves |
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fusiform initials
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cambium cells within the vascular bundles produce new vascular tissue
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suberin
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waxy material deposited by cork cells just before death, impedes water loss from stems
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periderm
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layers of cork plus cork cambium
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bark
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all tissues external to vascular cambium (phloem plus periderm)
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lenticels
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spongy regions in the bark that make it possible for living cells within the trunk to exchange gases with the outside air for cellular respiration
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water potential
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combined effects of solute concentration and pressure
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aquaporins
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a transport protein in the plasma membranes of a plant or animal cell that specifically facilitates the diffusion of water across the membrane (osmosis)
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symplast
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cytoplasmic continuum through plasmodesmata, maximizes absorption selectivity
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apoplast
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continuum of adjacent cell walls, maximizes exposure to cells for absorption
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bulk flow
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the movement of a fluid driven by pressure
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Casparian strip
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belt made of suberin (impervious to water and dissolved minerals), located in wall of each endodermal cell
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root pressure
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upward push of xylem sap from roots
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guttation
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exudation of water droplets (dew on morning leaf) forced through hydathodes (escape valves)
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transpirational pull
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loss of gaseous water in spongy mesophyll ---> evaporation from thin film of water that coats mesophyll cells ----> adhesion to pores of cell walls ----> cohesion to water in xylem (creates a concave meniscus and negative pressure)
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abscisic acid
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produced by mesophyll cells in response to water deficiency, signals guard cells to close stomata
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xerophytes
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plants adapted to arid climates - small, thick leaves; thick cuticle; stomata in depressions to shelter from wind; shedding of leaves; CAM (CO2 taken in at night so stomata can close in day)
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translocation
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transport of food in a plant via phloem
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sugar source
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plant organ in whcih sugar is being produced by either photosynthesis or the breakdown of starch
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sugar sink
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organ that consumes or stores sugar
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transfer cells
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numerous ingrowths of walls of companion cells, increases cell's surface area and enhances the transfer of solutes between apoplast and symplast
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nodules
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plant cells that contain nitrogen-fixing bacteria in th roots of legumes
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complete flowers
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have sepals, petals, stamens, and carpels
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incomplete flowers
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lacking one or more of sepals, petals, stamens, and carpels
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perfect flower
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has both stamens and carpels
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imperfect flower
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missing either stamens or carpels
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monoecious
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staminate and carpellate flowers are located on same individual plant
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dioecious
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staminate and carpellate flowers are located on separate plants
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contents of embryo sac (plants)
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egg cell, synergids (two cells that flank egg cell)
3 antipodal cells 2 polar nuclei |
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self-incompatible
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biochemical block prvents self-pollination in some plants
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hypocotyl
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embryonic axis below the part at which the cotyledons are attached
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radicle
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embryonic root, where hypocotyl terminates
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epicotyl
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portion of embryonic axis above cotyledons
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scutellum
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specialized type of cotyledon found in members of grass family
-very thin, large surface area against endosperm from which scutellum absorbs nutrients during germination |
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pericarp
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thickened wall of fruit (develops from wall of ovary)
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simple fruit
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fruit derived from single ovary (cherry)
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aggregate fruit
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results from single flower that has several carpels (blackberry)
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multiple fruit
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develops from group of flowers tightly clustered together (inflorescence)
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imbibition
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the absorption of water due to the low water potential of the dry seed - triggers germination (seed expands, ruptures, metabolic changes that cause embryo to resume growth)
causes embryo to release gibberellins, which signal for hydrolysis of stored foods in endosperm |
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vegetative reproduction
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plant species cloning themselves by asexual reproduction
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fragmentation
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the separation of a parent plant into parts that re-form whole plants
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apomixis
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production of seeds without fertilization of flowers
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auxins
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a class of plant hormones, including indoleacetic acid (IA), having a variety of effects, such as phototropic response through stimulation of cell elongation, stimulation of secondary growth, and the development of leaf traces and fruit
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cytokinins
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synthesized in roots, affect root growth and differentiation; stimulate cell division and growth; stimulate germination; delay senescence
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gibberellins
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a class of related plant hormones that stimulate growth in the stem and leaves, trigger the germination of seeds and breaking of bud dormancy, and stimulate fruit development with auxin
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abscisic acid
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inhibits growth; closes stomata during water stress; counteracts breaking of dormancy
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ethylene
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promotes fruit ripening; opposes some auxin effects; promotes or inhibits growth and development of roots, leaves, and flowers, depending on species
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senescence
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aging in plants
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oligosaccharins
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short chains of sugars released from cell walls by the hydrolytic action of enzymes on cellulose and pectin
trigger defense responses by plants that have been invaded by pathogens |
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brassinosteroids
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required for normal growth and development
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tropisms
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growth responses that result in curvatures of whole plant organs toward or away from stimuli
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statoliths
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specialized plastids containing dense starch grains, may be involved in gravitotropism
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thigmomorphogenesis
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developmental response to mechanical perturbation, usually results from increased production of ethylene in response to chronic mechanical stimulation
(i.e. wind on mountain ridge creates shorter, stockier trees) |
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photoperiodism
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a physiological response to day length, such as flowering in plants
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short-day plant
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a plant that flowers, usually in late summer, fall, or winter, only when the light period is shorter than a critical length
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long-day plant
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a plant that flowers, usually in late spring or early summer, only when the light period is longer than a critical length
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day-neutral plants
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plants that flower when they reach a certain stage of maturity, regardless of day length at that time
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phytochrome
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a pigment involved in many responses of plants to light
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660 nm light
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wavelength most effective in interrupting night length, can trigger long-day plant to flower even if the total night length exceeds the critical number of hours
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730 nm light
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wavelength that negates shortening of night length by 660 nm light, triggers flowering in short-day plants if preceded by 660 nm flash
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Pr
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Phytochrome synthesized when plants are kept in dark, converted to Pfr when pigment is exposed to red light
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Pfr
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phytochrome that triggers many of a plant's developmental responses to light, such as the germination of seeds that require light to break dormancy
far-red light converts it back to Pr |
