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589 Cards in this Set

  • Front
  • Back
molecules that are mirror images of each other
structural isomers
diferent covalent arrangments of atoms
geometric isomers
different spatial arrangements of atoms
hydrogen atom bonded to oxygen atom (alcohols)
carbon atom joined to oxygen atom
organic compound with carbonyl group at end of skeleton
organic compound with carbonyl group not at end of carbon skeleton
oxygen atom double bonded to carbon atom also to hydroxyl group (-COOH), called carboxylic acids or organic acids
amino group
sulfydryl group
-SH, compounds called thiols
phosphate group
Pentose sugars (examples)
Ribose, ribulose
Hexose Sugars (examples)
glucose, galactose, fructose
Monosaccharides (examples)
glyceraldehyde, ribose, glucose, galactose, fructose
disaccharides (examples)
maltose, sucrose, lactose
glycosidic linkage
covalent bond formed between two monosacharides by dehydration reaction
polysaccharides (examples)
starch, glycogen, cellulose, chitin
fatty acid
glycerol with long carbon skeleton
alcohol with thre carbons, each bearing a hydroxyl group
ester linkage
C-O-C bond (i.e., between glycerol, fatty acid)
saturated fatty acid
no double bonds between carbon atoms in tail
unsaturated fatty acid
one or more double bonds (kink in shape) in tail
two fattyt acids as opposed to 3, third is to phosphate group (attached to glycerol)
fat (triacylglycerol)
3 fatty acids each joined to glycerol, hydrophobic because of non-polar (-H bonds in fatty acid tail)
phospholipid droplet with hydrophilic phosphate heads on outside
lipid, carbon skeleton consisting of four fused rings
steroid, component of animal cell membranes, precursor to fusion of other steroids
amino acid
organic compound possessing carboxyl, amino, R groups
R group or side chain
variable group that differs for amino acids
peptide bond
covalent bond between amino acids, dehydration reaction between amino, carboxyl groups
primary structure
unique sequence of amino acids
secondary structure
polypeptide chain folded/coiled in patterns - result from hydrogen bonds at regular intervals along polypeptide backbone
alpha helix
secondary structure, delicate coil (lysozyme)
pleated sheet
two regions of polypeptide chain lie parallel to each other, held together by hydrogen bonds
tertiary structure
irregular contortions from bonding between side chains
hydrophobic interaction
clustering of amino acids with hydrophobic (nonpolar) side chains cluster at core of protein, out of contact with water
disulfide bridges
strong covalent bonds between sulfhydryl (-SH) side chains (forms -S-S-)
quaternary structure
overall protein structure that results from aggregation of polypetide subunits (collagen, hemoglobin)
chaperone proteins
molecules that function as temporary braces in assisting the folding of other proteins
monomers of nucleic acids, contain nitrogenous base, pentose, phosphate groups
difference between deoxyribose, ribose
deoxyribose lacks oxygen atom on number two carbon
phosphodiester linkages
covalent bonds between phosphate of one nucleotide and sugar of next
totality of organism's chemical processes
catabolic pathways
release energy by breaking down complex molecules
anabolic pathways
consume energy to build complicated molecules from simpler ones
adenine bonded to ribose with chain of three phosphates attached to ribose, hydrolysis results in ADP+P(i) + Energy
phosphorylated intermediate
coupling of ATP hydrolysis directly to some other molecule
chemical agent that changes the rate of reaction w/o being consumed in reaction
induced fit
held by hydrogen and ionic bonds
interaction with one substrate molecule triggers the same favorable conformational change in all other subunits of enzyme
resolving power
measure of clarity of an image, minimum distance two points can be separated and still be distinguished as two separate points
region of prokaryotic cell where genetic material is concentrated
network of membranous tubules and sacs in the ER
functions of smooth ER
synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poisons
functions of rough ER
synthesis of secretory proteins, secretion through transport vesicles, membrane production
Golgi apparatus
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
membrane-bounded sac of hydrolytic enzymes, low pH (5) maintained by pumping hydrogen ions from cytosol into lumen of lysosome
recycling of cell's own organic material
membrane enclosing central vacuole in plant cells
stores organic compounds, inorganic ions, pigments, poisons
convoluted infoldings of inner membrane of mitochondrion
mitochondrial matrix
compartment of mitochondria enclosed by inner membrane
memranous system of flattened sacs in chloroplast
stacked thylakoids
fluid outside of thylakoids in chloroplasts
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
network of fibers extending through cytoplasm - motility, structure
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
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)
intermediate filaments
fibrous proteins supercoiled into thicker cables, maintenance of cell shape (tension-bearing elements), anchorage of nucleus and other organelles, formation of nuclear lamina
region of nucleus from which microtubules grow out
two in each centrosome, each composed of nine sets of triplet microtubules arranged in ring
nine doublets of microtubules arranged in ring
basal body
anchors microtubule assembly in cilium or flagellum, structurally identical to centriole
large protein making up basal motors
cytoplasmic streaming
circular flow of cytoplasm within cell to speed distribution of materials within cel
middle lamella
thin layer rich in sticky polysaccharides (pectin), center of cell wall
extracellular matrix
glycoproteins (collagen, fibronectins, integrins) that support cell, also help in adhesion, movement, regulation
perforations in cell walls that form channels
tight junctions
connections that form continuous belts around cell, fusion between membranes of adjacent cells
desmosomes (anchoring junction)
function like rivets, fastening cells together into strong epithelial sheets, reinforced by intermediate filaments
gap junctions (communicating junctions)
provide cytoplasmic channels between adjacent cells
has both hydrophobic and hydrophilic regions
integral proteins
generally transmembrane proteins, hydrophobic regions that completely span hydrophobic interior of membrane
peripheral proteins
proteins not embedded in lipid bilayer
What is the lipid bilayer permeable to?
small, polar, uncharged molecules (water, ethanol)
transport proteins
transport specific ions and polar molecules
facilitated diffusion
diffusion facilitated with the help of transport proteins
membrane potential
voltage across a membrane
electrogenic pump
transport protein that generates membrane potential
proton pump
actively transports hydrogen ions out of cell
when one ATP-powered pump indirectly drives the active transport of several other solutes
extracellular substances that bind to the receptors on proteins
breakdown of glucose (energy)
-686 KCal (-2870 KJ) per mole
loss of electrons from substance
addition of electrons to a substance
coenzme, oxidizing agent in cell respiration
enzyme that removes a pair of hydrogen atoms from the substrate
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
energy-investment phase (glycolysis)
cell spends ATP to phosphorylate fuel molecules
energy-payoff phase
ATP is produced by substrate phosphorylation, NAD+ is reduced to NADH
enzymes in glycolysis
hexokinase, phosphofructokinase - transfer phosphate group from ATP to organic sugar
oxidative phosphorylation
using an electron transport chain to combine hydrogen ions and molecular oxygen into water
substrate-level phosphorylation
enzyme transfers a phosphate group from a substance to ADP
link reaction
mitochondria, pyruvate ---> acetyl CoA, NAD+ -----> NADH, releases CO2
coenzyme A
catalyzes pyruvate ----> acetyl CoA
Krebs Cycle
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)
electron transport chain
located in inner membrane of mitochondria
proteins in the electron transport chain
ATP synthase
enzyme that makes ATP using energy of existing ion gradient
cell respiration (total energy)
36-38 ATP, 7.3 kcal per mole of ATP
alcohol fermentation (conversion)
glycolysis plus reactions that regnerate NAD+, transfer electrons from NADH to pyruvate
lactic acid fermentation
pyruvate reduced directly by NADH to form lactate as a waste product, no release of CO2
facultative anaerobes
(yeasts, bacteria) can make ATP to survive in anaerobic or aerobic respiration
catabolism of proteins
proteins ----> amino acids ----> deamination in glycolysis-----> Krebs cycle
catbolism of fats
fats -----> glycerol -----> glycolysis
fatty acids ----> acetyl CoA (beta oxidation)
inhibited by citrate, ATP
stimulated by AMP
tissue in the interior of the leaf
light reactions
first stage of photosynthesis
H20+Light+NADP+ + ADP+Pi ----> 02+NADPH +H+ + ATP
Calvin cycle
second stage of photosynthesis (dark reaction)
CO2+NADPH+ATP ----> CH20 + NADP+ + ADP + Pi
electron acceptor for light reaction
generation of ATP by powering the addition of a phosphate group to ADP using light energy
carbon fixation
incorporation of carbon into organic compounds
absorption spectrum
graph plotting a pigment's light absorption versus wavelength
action spectrum
wavelength vs. measure of photosynthetic rate
chlorophyll a
blue-green, participates directly in light reactions
chlorophyll b
accessory pigment, absorbs light and transfers energy to chlorophyll a, yellow-green
accessory pigments, hydrocarons that are various shades of yellow and orange
photosystem I
P700 reaction center, best at absorbing far-red light (700 nm), electrons from photosystem II reduce NADP+ to NADPH
photosystem II
P680 reaction center, electrons come from H20, produces O2, photophosphorylation
location of Calvin cycle
location of light reaction
thylakoid membrane
location of release of H+, O2
thylakoid space
cyclic electron flow
produces ATP by sending electron in photosystem I back down electron transport chain
glyceraldehyde 3-phosphate (G3P)
carbohydrate produced directly from Calvin cycle
carbon fixation in Calvin cycle
CO2 ----> ribulose biphosphate (RUBP), catalyzed by rubisco
reduction in Calvin cycle
NADPH gives electrons to G3P
regeneration (Calvin cycle)
G3P ---> RuBP
output of Calvin cycle
1 G3P, which goes to glucose and other organic compounds, NADP+
C3 plants
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
process of rubisco accepting O2
C4 plants
carbon fixation forms four-carbon compound (sugarcane, corn)
bundle-sheath cells
(C4 plants), tightly-packed sheets around veins of leaf
mesophyll cells
(C4 plants) - loosely arranged between bundle sheath, leaf surface
PEP Carboxylase
in C4 plants, adds CO2 to PEP - higher affinity than rubisco, can fix CO2 efficiently when CO2 levels are low (stomata are partially closed)
CAM plants
crassulacean acid metabolism (succulent plants)
organic acids made in night provide CO2 in day when stomata are closed
sister chromatids
identical copies of chromosome's DNA molecule in duplicated chromosome, intially attached along lengths
narrow "waist" at specialized region of chromosome
90% of mitotic cycle, cell growth, chromosomes copied
G1 phase, S phase, G2 phase
G1 Phase
interphase, cell growth
S phase
interphase (synthesis), duplication of chromosomes
G2 Phase
interphase, growth and preparation for cell division
mitotic spindle
fibers made of microtubules, associated proteins, begins to form in cytoplasm during prophase (protein tubulin)
microtubule organizing center, has two centrioles in center (animal cells), replicates during interphase, separate in prophase, prometaphase
structure of proteins and specific sections of chromosomal DNA at centromere, located in each chromatid
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
fragmentation of nuclear envelope, microtubules interact with condensed chromosomes, microtubules extend from each pole toward middle of cell
chromosomes convene on metaphase plate (plane equidistant between spindle's two poles), centrosomes at opposite poles of cell
centromeres alligned
microtubules attached to kinetochores
paired centromeres separate, sister chromatids move to opposite corners of cell
daughter nuclei form at two poles of cell, nuclear envelopes arise out of parent cell's nuclear envelope, chromatin becomes more loosely coild
division of cytoplasm, hastened by actin, myosin
cleavage furrow
shallow groove in cell surface near old metaphase plate, right before cytokinesis
cell plate
cytokinesis in plant cells, produced by vesicles derived from Golgi apparatus that move along microtubules to the center of the cell
binary fission
cell division in prokaryotes, circular chromosome is replicated, move to opposite corners, then cytokinesis
cyclin-dependent protein kinases
signals for cell division to continue at checkpoints
protein that activates kinase by attaching to it
CDK complex that triggers mitotic stage in cells
growth factor
protein relased by certain body cells that stimulates other cells to divide
cancer cells
no density-dependent nor anchorage-dependent division
a gene's specific location along the length of a chromosome
homologous chromosomes
the chromosomes that move up a pair, each carrying genes controlling the same inherited characters
chromosomes other than sex chromosomes
cell with a single chromosome set
fertilization of gametes
fertilized egg
Interphase I
same as mitosis interphase
Prophase I
chromosomes condense, synapsis, other cellular components - same as mitosis
prophase I of meiosis, homologous chromosomes come together as pairs - forms tetrads
crossings of homologous chromosomes that hold them together
metaphase I
same as mitosis metaphase
anaphase I
sister chromatids remain attached at centromeres, move as single unit to same poles
telophase I/cytokinesis
cells become haploid
prophase II
spindle apparatus forms
metaphase II,etc
results in four haploid daughter cells
sexual variation
independent assortment of chromosomes, crossing over, random fertilization
crossing over
occurs in prophase of meiosis I, genetic exchanges occur at chiasmata
random fertilization
i.e., different possible sperm
incomplete dominance
the F1 hybrids have an appearance somewhere in between the phenotypes of the two parental varieties
both alleles are separately manifest in the phenotype (blood type)
ability of a gene to affect an organism in many ways
a gene at one locus alters the phenotypic expression of a gene at another locus
cystic fibrosis
defection chloride channels causes thicker mucus
Tay-Sachs disease
recessive allele - dysfunctional enzyme that gails to break down brain lipids - Ashkenazie Jews
sickle-cell anemia
substitution of amino acid in hemoglobin protein of red blood cells
Huntington's disease
dominantly inherited, degenerative disease of nervous system, affects individuals at 35-45 years of age
14th-16th week of pregnancy, amniotic fluid withdrawn from uterus
chorionic villus sampling (CVS)
suctions off small amount of featl tissue from the placenta, occurs in 8th to 10th week of pregnancy
sex-linked genes
genes located on a sex chromosomes
linked genes
genes located on the same chromosome tend to be inherited together in genetic crosses because the chromosome is passed along as a unit
offspring that have different genotypes than the parents
Barr body
inactive X in each cell of a female condenses into a compact object
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
abnormal chromosome number resulting when either of the aberrant gametes unites with a normal one at fertilization (nondisjunction)
gamete missing a chromosome
chromosomal alteration in which an organism as more than two complete chromosome sets
chromosomal fragment lacking a centromere is lost during cell division
deleted chromosome reattached in reverse orientation
fragment joins nonhomologous chromosome
Klinefelter's syndrome
XXY (male) - sterile, abnormally small testes
Jacobson's syndrome
XYY, taller, aggressive
cannot be distinguished from XX females except by karyotype
Turner's syndrome
XO, no maturation of sex organs, no secondary sex characteristics, sterile, short
genomic imprinting
certain gnes imprinted in each generation depending on whether gene resides in female or male
fragile X syndrome
abnormal X chromosome, tip hangs onto rest of chromosomes by a thin thread of DNA
mental retardation - caused by maternal imprinting
Frederic Griffith
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)
a change in genotype and phenotype due to the assimilation of external DNA by a cell
Oswald Avery
along with McCarty and MacLeod, announced that transforming agent was DNA (1944)
viruses that infect bacteria
Hershey and Chase
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
Erwin Chargaff
1947, found that nitrogenous bases are present in characteristic ratio in all organisms
James Watson and Francis Crick
1950's, determined that DNA structure was double helix, model explaied Chargaff's rule
semiconservative model of replication
two strands of parental molecule separate, each functions as a template for synthesis of a new complementary strands
Meselson, Stahl
1950s, tested three alternative hypotheses for DNA regulation
cultured E coli with nitrogen isotope, tracked resulting DNA, supported semiconservative model
origins of replication
sites of beginning of DNA replication
replication fork
Y-shaped region where new strands of DNA are elongating
DNA polymerases
catalyze elongation of DNA, add nucleotides to new DNA strands
leading strand
the new continuous complementary DNA strand synthesized along the template strand in the mandatory 5'-->3' direction
lagging strand
a discontinuously synthesized DNA strand that elongates in a direction away from the replication fork
Okazaki fragments
pieces of lagging strand that are syntheized each in 5' ---> 3' direction but overall in 3' --> 5' direction
DNA ligase
joins Okazaki fragments of lagging strand into a single strand
original preexisting chain in DNA replication, RNA, converted to DNA before ligase
enzyme that joins RNA nucleotides to make primer (10 nucleotides long)
enzyme that untwists the double helix at the replication fork
single-stranded binding protein
hold DNA strands apart while they serve as templates for complementary strands
mismatch repair
enzyme that fixes mistakes when DNA is copied
DNA-cutting enzyme
excision repair
DNA repair involving nuclease, repair synthesis
nucleotide sequences at end of strand - repetitions of short nucleotide sequences, prevent ends from activating cell's systems for monitoring DNA damage
enzyme that catalyzes the lengthening of telomeres, contains RNA molecule that seves as template for new telomere segments
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
the synthesis of RNA under the direction of DNA
messenger RNA
transcript of gene's protein-building instructions
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
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
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
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
noncoding segments of nucleic acid that lie beween coding regions
other regions of nucleic acids that are eventually expressed
a complex assembly that interacts with the ends of an RNA intron in splicing RNA; reases an intron and joins the two adjacent exons
RNA molecules that function as enzymes
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
nucleotide triplet which binds to complementary codon on mRNA
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
codon recognition, peptide bond formation, translocation
release factor binds to stop codon in A site, does not move to E site
strings of ribosomes that are attached to one messenger RNA molecule
signal peptide
polypeptides or proteins destined for the endomembrane system or for secretion
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
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
a phage genome that has been inserted into a specific site on the bacterial chromosome
viral DNA that inserts into a host genome
RNA virus that has genetic information which flows the reverse way
reverse transcriptase
enzyme that transcribes DNA from an RNA template
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
tiny molecules of naked circular RNA that infect plants
infectious proteins
dense region of DNA in bacteria
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
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
small, circular, self-replicating DNA molecule separate from the bacterial chromosome
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
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
segment of DNA that acts as a switch for gene expression for certain enzymes
the entire stretch of DNA required for enzyme production for the tryptophan pathway (operator, promoter, genes controlled)
protein that binds to operator, switching off operon
regulatory gene
gene that codes for repressor protein
small molecule that cooperates with a repressor protein to switch an operon off
enztme that catalyzes hydrolysis of lactose into glucose and galactose
a specific small molecule that inactivates repressor
cyclic AMP (cAMP)
accumulates when glucose is absent
cAMP receptor protein (CRP)
regulatory protein, activator of transcription
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
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
highly-condensed interphase chromatin
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
cancer-causing cells
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)
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
brief electrical pulse applied to solution containing cells in order to make transformation more efficient
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
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
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
the coexistence of two or moe distinct forms of individuals (polymorphic characters) in the same population
geographical variation
differences in genetic structure between populations
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
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)
(plants), an individual that has more than two chromosome sets, all derived from a single species, can cause sympatric speciation
contribution of two different species to a polyploid hybrid
punctuated equilibrium
species diverge in spurts of relatively rapid change instead of slowly and gradually
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
the evolutionary history of a species or a group of related species
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
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
aggregates of abiotically produced molecules
modified sugars corss-linked by short polypeptides that vary from species to species - major component of bacterial cell walls
presence of peptidoglycan, bacteria that are gram-negative (no peptidoglycan) are more threatening because they are more resistant to antibiotics and are often toxic
inhibits synthesis of cross-links in peptidoglycan and prevents the formation of a functional wall
protective layer around the outside of the prokaryotic cell
movement toward or away from a stimulus
thick-coated, resistant cells procued within a bacterial cell exposed to harsh conditions
photosynthetic organisms that harness light energy to drive the synthesis of organic compounds from carbon dioxide
need only CO2 as a carbon source, obtain energy by oxidizing inorganic substances
use light to generate ATP but must obtain their carbon in organic form
must consume organic molecules for both energy and carbon
decomposers that absorb their nutrients from dead organic matter
nitrogen fixation
prokaryotes convert N2 to NH3
bacteria oxidize ammonium to nitrite (NO2-) and then to nitrate (NO3-)
nitrate converted back to N2 by prokaryotes
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
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
pathogens that cause illness when the host's defenses are weakened
proteins secreted by prokaryotes (i.e., botulism)
components of the outer membranes of certain gram-negative bacteria (Salmonella)
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)
mutualistic collectives of green algae and fungi
flagellated sperm fertilizing a nonmotile egg
the substance that hardens the cell walls of "wood" tissues in plants
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
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
male gametangium
female gametangium
a capsule in fungi and plants in which meiosis occurs and haploid spores develop
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
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
create single type of spore which develops into bisexual gametophyte (most ferns)
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
plants that use another organism as a substratum but are not parasites
a sporophyte embryo packaged along with a food supply within a protective coat
solid, fleshy structure - megasporangium in seed plants
additional layers of sporophyte tissues that envelop the megasporangium in seed plants
entire structure of integuments, nucellus, megaspores
microsopores in seed plants
pollen, which elongates tube to discharge sperm within the ovule, sperm generally lack flagella
a vascular plant that bears naked seeds not enclosed in any specialized chambers
gymnosperm with cone that is cluster of scale-like sporophylls, generally have tracheids
a flowering plant, which forms seeds inside a protective chamber called an ovary, generally have vessel elements
opening between integuments in gymnosperms
cell that reinforces xylem in angiosperms, also evolved from tracheid
reproductive structure of angiosperm
a whorl of modified leaves in angiosperms that encloses and protects the flower bud before it opens
brightly-colored, help attract insects in angiosperms
pollen-producing male reproductive organ of a flower, consisting of an anther and a filament
the female reproductive organ of a flower, consisting of the stigma, style, and ovary
stalk in the stamen (male)
where pollen is produced, terminal sac in stamen
sticky tip of carpel that receives pollen
similar to filament, stalk of carpel (female)
ovary (flower)
portion of a carpel in which the egg-containing ovules develop
mature ovary
pollen grains
immature male gametophyte, develops within anthers of stamen
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
the one (monocot) or two (dicot) seed leaves of an angiosperm embryo
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
mutual evolutionary influence between two species
mostly multicellula, eukaryotic, heterotrophic (absorption), either sexual or asexual reproduction
minute threads composed of tubular walls surrounding plasma membranes and cytoplasm
interwoven mat of hyphae
cross-walls that divide hyphae into cells, large pores to allow ribosomes, mitochondria, nuclei to flow from cell to cell
strong but flexible nitrogen-containing polysaccharide
referring to a multinucleated condition resulting from the repeated division of nuclei without cytoplasmic division
in parasitic fungi, nutrient-absorbing hyphal tips that penetrate the tissues of the host
fungal sexual reproduction
plasmogamy (fusion of cytoplasm), karyogamy (fusion of nuclei), dikaryon (two nuclei)
mutualistic associations of plant roots and fungi
a type of reproduction in which females produce offspring from unfertilized eggs
longitudinal, flexible rod located between the digestive tube and the nerve cord
amniotic egg
shelled, water-retaining
single cotyledon, parallel veins, complexly-arranged vascular bundles, fibrous root systems, floral parts=multiples of 3
two cotyledons, netlike veins, vascular bundles=ring, taproot, four or five floral parts
vascular tissue that conveys water and dissolved minerals upward from roots into the shoots
vascular tissue which transports food made in mature leaves to the roots and to parts of the shoot system
root absorption
root hairs, mycorrhizae
any plant part that grows in an unusual location
stem segments between nodes
axillary bud
potential to form branch shoot, in angle formed by each leaf and the stem
points at which leaves are attached
terminal bud
bud at apex of shoot
apical dominance
presence of terminal bud inhibits growth of axillary bud
stalk of leaf that joints it to node of stem
parenchyma cells
relatively unspecialized; thin, flexible primary walls
metabolic functions=task
collenchyma cells
thicker primary walls, grouped in strands of cylinders
-support without restraining growth (no secondary walls or lignin)
sclerenchyma cells
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)
dead at functional maturity, secondary walls, spiral/ring pattern
long, thin cells, tapered, also function in support, water moves primarily through pits
thinner regions of tracheids and vessel elements where only primary walls are present
vessel elements
water-conducting cells of xylem; wider, shorter, thinner-walled, less tapered
sieve-tube members
chains of cells that transport sucrose, other organnic compounds, and some mineral ions through phloem
sieve plates
end walls between sieve-tube members
pores that facilitate the flow of fluid from cell to cell along the sieve tube
companion cell
connected to sieve-tube member by plasmodesmata
plants that live many years
perpetually embryonic tissues
primary growth
elongation at apical meristem
secondary growth
progressive thickening of the roots and shoots formed earlier by primary growth (occurs in gymnosperms, most dicots, but few monocots)
root cap
protects delicate root meristem during elongation
quiescent center
a region located within the zone of cell division in plant roots, containing meristematic cells that divide very slowly
the outermost primary meristem, which gives rise to the epidermis of roots and shoots
a primary meristem of roots and shoots that forms the vascular system
ground meristem
a primary meristem that gives rise to ground tissue in plants
vascular bundle of both xylem and phloem, results from procambium
central core of parenchyma cells in stele of monocot roots
ground tissue (parenchyma cells) in roots (between stele and epidermis)
innermost layer of cortex, cylinder one cell thick that forms the boundary between the cortex and the stele
outermost layer of stele
vascular bundle
several strands of vascular tissue that run length of stem
guard cells
epidermal cells that flank stomata
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
the evaporative loss of water from a plant
ground tissue of a leaf, sandwiched between upper and lower epidermis, consists of parenchyma cells with chloroplasts, specialized for photosynthesis
upper mesophyll
palisade parenchyma (columnar cells)
lower mesophyll
spongy parenchyma (labyrinth of air spaces through which carbon dioxide and oxygen circulate around irregularly shaped cells)
phase changes
apical meristem changes from one developmental phase to another
secondary plant body
tissues produced in secondary growth
vascular cambium
in secondary growth, produces secondary xylem (to the interior) and phloem (to the exterior)
cork cambium
produces a tough, thick covering for stems and roots that replaces the epidermis, produces cork cells externally
ray initials
cambium cells that produce radial files of parenchyma cells (xylem, phloem rays)
radial transport of water, nutrients
storage of starch, other reserves
fusiform initials
cambium cells within the vascular bundles produce new vascular tissue
waxy material deposited by cork cells just before death, impedes water loss from stems
layers of cork plus cork cambium
all tissues external to vascular cambium (phloem plus periderm)
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
water potential
combined effects of solute concentration and pressure
a transport protein in the plasma membranes of a plant or animal cell that specifically facilitates the diffusion of water across the membrane (osmosis)
cytoplasmic continuum through plasmodesmata, maximizes absorption selectivity
continuum of adjacent cell walls, maximizes exposure to cells for absorption
bulk flow
the movement of a fluid driven by pressure
Casparian strip
belt made of suberin (impervious to water and dissolved minerals), located in wall of each endodermal cell
root pressure
upward push of xylem sap from roots
exudation of water droplets (dew on morning leaf) forced through hydathodes (escape valves)
transpirational pull
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)
abscisic acid
produced by mesophyll cells in response to water deficiency, signals guard cells to close stomata
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)
transport of food in a plant via phloem
sugar source
plant organ in whcih sugar is being produced by either photosynthesis or the breakdown of starch
sugar sink
organ that consumes or stores sugar
transfer cells
numerous ingrowths of walls of companion cells, increases cell's surface area and enhances the transfer of solutes between apoplast and symplast
plant cells that contain nitrogen-fixing bacteria in th roots of legumes
complete flowers
have sepals, petals, stamens, and carpels
incomplete flowers
lacking one or more of sepals, petals, stamens, and carpels
perfect flower
has both stamens and carpels
imperfect flower
missing either stamens or carpels
staminate and carpellate flowers are located on same individual plant
staminate and carpellate flowers are located on separate plants
contents of embryo sac (plants)
egg cell, synergids (two cells that flank egg cell)
3 antipodal cells
2 polar nuclei
biochemical block prvents self-pollination in some plants
embryonic axis below the part at which the cotyledons are attached
embryonic root, where hypocotyl terminates
portion of embryonic axis above cotyledons
specialized type of cotyledon found in members of grass family
-very thin, large surface area against endosperm from which scutellum absorbs nutrients during germination
thickened wall of fruit (develops from wall of ovary)
simple fruit
fruit derived from single ovary (cherry)
aggregate fruit
results from single flower that has several carpels (blackberry)
multiple fruit
develops from group of flowers tightly clustered together (inflorescence)
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
vegetative reproduction
plant species cloning themselves by asexual reproduction
the separation of a parent plant into parts that re-form whole plants
production of seeds without fertilization of flowers
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
synthesized in roots, affect root growth and differentiation; stimulate cell division and growth; stimulate germination; delay senescence
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
abscisic acid
inhibits growth; closes stomata during water stress; counteracts breaking of dormancy
promotes fruit ripening; opposes some auxin effects; promotes or inhibits growth and development of roots, leaves, and flowers, depending on species
aging in plants
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
required for normal growth and development
growth responses that result in curvatures of whole plant organs toward or away from stimuli
specialized plastids containing dense starch grains, may be involved in gravitotropism
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)
a physiological response to day length, such as flowering in plants
short-day plant
a plant that flowers, usually in late summer, fall, or winter, only when the light period is shorter than a critical length
long-day plant
a plant that flowers, usually in late spring or early summer, only when the light period is longer than a critical length
day-neutral plants
plants that flower when they reach a certain stage of maturity, regardless of day length at that time
a pigment involved in many responses of plants to light
660 nm light
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
730 nm light
wavelength that negates shortening of night length by 660 nm light, triggers flowering in short-day plants if preceded by 660 nm flash
Phytochrome synthesized when plants are kept in dark, converted to Pfr when pigment is exposed to red light
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