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155 Cards in this Set
- Front
- Back
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molecules of life |
lipids, carbs, proteins, nucleic acids |
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macromolecules |
carbs, proteins, nucleic acids polymers |
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polymers |
many monomers covalently linked assembled by dehydration reactions broken down by hydrolysis (molecule of water added to break the bond between monomers) can be linear arrangements, can be branched
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monomers |
"building block" molecules of a polymer attached together by loss of molecule of water
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homopolymers |
composed of identical monomers (starch is polymerized glucose)
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functions of carbs |
energy storage -glycogen in muscle and liver -starch in plants energy transport -glucose in blood -sucrose in plants building material -cellulose in plant cell walls -chitin in arthropod skeletons molecular recognition and communication at the cell surface -membrane glycoproteins and glycolipids (MHC complex on cell surface) |
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carbs |
simple sugars and their polymers polyhydroxy aldehydes or ketones (CH2O)n
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monosaccharide characteristics |
3-7 carbons functional groups: hydroxyl and carbonyl -aldose: possess an aldehyde group, HCOR -ketose: possess a ketone group, RCOR isomeric forms: arrangement of groups on asymmetric carbon atoms (glucose, galactose) straight chain/ring forms: ring form predominates in aqueous soln at pH 7 |
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fischer projection |
straight chains |
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haworth projection |
ring structure |
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disaccharides |
2 monosaccharides attached by glycosidic linkage (can be same or different) |
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glycosidic linkage |
covalent bond between 2 monosaccharides by dehydration reaction |
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isomers |
orientation of -H and -OH groups on #1 carbon in a ring (alpha and beta glucose) |
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oligosaccharides |
several monosaccharides attached together often covalently linked to noncytoplasmic side of proteins (glycoproteins) and lipids (glycolipids) |
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storage polysaccharide |
starch: main storage polysaccharide of plants and algae glycogen: main storage polysaccharide of animals |
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starch |
consists of amylose (linear polymer with 1-4 glycosidic linkages) and amylopectin (like amylose but with 1-6 branches) in the shape of a helix dietary sources: potatoes, wheat, corn, rice |
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glycogen |
similar to amylopectin, but more frequent branch points |
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amylases |
digest (hydrolyze) starch and glycogen |
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structural polysaccharides |
cellulose: principal component of plant cell walls chitin: principal component of arthropod skeletons and fungal cell walls
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cellulose |
most abundant polysaccharide in nature glycosidic linkages B(1-4) unbranched, straight, not helical (hydroxyl groups can H bond to those on other cellulose molecules lying parallel to it, forming microfibrils - good building material!) |
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animals lack cellulases |
cows and termites can use cellulose because they harbour bacteria in guts which make cellulases animals that lack symbionts cannot derive nutrition from plant cell walls very few animals produce cellulases - slugs and snails some fungi make cellulases |
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chitin |
homopolymer of a monosaccharide derivative, N-acetylglucosamine second most abundant polysaccharide in nature |
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lipid properties |
hydrophobic (often has hydrophilic functional groups attached) hydrophobic regions soluble in nonpolar solvents hydrophilic regions soluble in water |
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lipid examples |
fatty acids triglycerides phospholipids steroids and sterols waxes |
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lipid functions |
energy storage -store 2x as much energy as carbs gram for gram (compact fuel reserve) fuel molecules -fatty acids are oxidized in mito, ATP produced as result membrane formation -phospho and glyco lipids spontaneously self assemble into bilayers in aqueous solution communication -steroid hormones, secondary messengers protection -adipose tissue cushions organs insulations -adipose tissue has low thermal conductivity (Body covering) |
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fatty acids |
CH3(CH2)nCOOH two parts: unbranched, hydrophobic hydrocarbon chain and hydrophilic carboxyl group
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amphipathic |
molecules with hydrophobic and hydrophilic region |
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aspects of structural variation in fatty acids |
length of carbon chain (usually 16-18) saturated or unsaturated (double bonds) cis or trans configuration at double bonds |
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triacylglycerols/triglycerides |
commonly known as fats and oils glycerides are fatty acid esters of glycerol animal fats solid at RT -mostly saturated -molecules stack in regular arrays with many contacts between them -higher heat needed to disturb -diets high in sat fats are associated w/heart disease and cancer plant fats are oils -unsaturated -molecules stack irregularly w/few contacts -lower heat to disrupt interactions |
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monounsaturated fats |
best for health canola oil, olive oil
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membrane lipids |
phospoglygerides, sphingolipids, membrane steroids (cholesterol) amphipathic form bilayers in aqueous soln |
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micelle formation |
favoured when cross sectional area of head group is greater than that of side chains |
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bilayer formation |
favoured when cross sectional area of head group is each to side chains phospholipids
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liposome |
sphere in which a phospholipid bilayer encloses an aqueous compartment |
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steroids |
carbon skeleton with four fused rings cholesterol |
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cholesterol |
rigid, planar, amphipathic constituent of animal cell membranes -function in membrane: stabilize at high temps by restraining movement of phospholipids -in humans: also keeps membrane fluid at low temps precursor of steroid hormones |
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hydrophobic interactions |
why oil and water dont mix water molecules form H bonds among themselves but not with hydrocarbon chains - water excludes hydrocarbons not an active repulsion, preference; water does not repel oil as 2 similar charges repel |
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van der waals interactions |
attractive forces between hydrophobic molecules - only attractive between hydrophobic, but can be forces between any other molecules electrons on neighbouring molecules briefly push past each other out of the way -local regions of electron presence associate with local regions of electron absence in the other molecule |
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proteins |
polymers of amino acids most amino acid polymerization occurs during translation |
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protein functions |
catalysis -enzymes defense -antibodies (immunoglobulins) structural support -collagen and elastin in animal CT -keratin in hair, horns, feathers transport -hemoglobin -membrane transporters storage -ovalbumin in egg -casein in mammal milk -glutens in wheat seeds -zeins in corn seed communication -hormones (insulin) -cell surface receptors movement -actin, myosin -tubulin, dynein (motor proteins) in microtubules regulators of gene expression antifreeze (fish)
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amino acid monomers |
side chain R group possess an amino group and a carboxyl group at least one asymmetric carbon (alpha carbon) - exception is glycine present in cells as only one optical isomer (L) zwitterions at pH 7
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non polar amino acids |
hydrophobic usually found in the center of the protein also found in proteins which are associated with cell membranes |
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polar uncharged amino acids |
hydrophilic and can form H bonds |
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electrically charged amino acids |
charge changes when pH changes low pH: groups are protonated, lots of protons around high pH: groups are unprotonated, few protons around |
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peptide bonds |
amino acids joined by dehydration reactions to give peptide bond compound consisting of 2 or more amino acids |
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polypeptides |
any string of amino acids, functional or not 10 or more amino acids but less than 50 |
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protein classification |
50 or more amino acids complete and folded into an active conformation; a protein consists of one or more polypeptide chains |
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oligopeptides |
10 or fewer amino acids |
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primary structure |
linear order of amino acids in polymer N and C terminus built in N-C direction during translation of mRNA backbone: NCCNCCNCC...
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secondary structure |
regions of regular repetitive structure stabilized by H bonds formed between backbone regions alpha helix, beta strand, beta pleated sheet |
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tertiary structure |
overall bending and folding of polypeptide chain into 3D shape stabilized mainly by interaction between R groups -H and ionic bonds, hydrophobiv interactions, disulfide bridges can be altered by environmental changes |
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quarternary structure |
association of more than one polypeptide chain to form an intact protein transthyretin is four identical polypeptide units
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genes |
info to build proteins stored here put to use in the process of gene expression
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conformation (shape) |
influences protein function results partly from primary structure -change primary structure>change shape>change function depends parly on weak interactions (can be denatured) many proteins can flip between conformations (and functions/activities) |
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denaturation |
interactions disrupted>protein unravels and loses conformation>function of protein altered or destroyed |
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protein structure and function |
may depend on a non protein helper (cofactor) ex. iron and heme group of hemoglobin
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protein folding |
some fold spontaneously some require help in folding other misfold
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chaperones |
proteins that facilitate protein folding molecular chaperones -help proteins fold is incompletely folded or partly denatured -ATP dependant process chaperonins -massive macromolecular chaperones that provide an internal cavity in which some proteins fold -also ATP dependant chaperones fo not dictate a proteins final structure; they help sheild a protein from unfavourable environmental influences |
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factors that help determine a proteins secondary, tertiary, and quarternary structure |
primary structure -determines location of alpha helices, beta strands, ionic bonds, SS bonds environmental condition -changes in pH, temp and [salt] can denarture a protein -renaturation is possible for some even a single amino acid in a proteins primary structure can alter its other levels of structure and functional ability (sickle cell disease)
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nucleic acids |
used in storage and transfer of genetic info DNA and RNA monomers = nucleotides polymers = polynucleotide strands |
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nucleotides |
pentose (five carbon sugars) nitrogenous base phosphate group nucleic acid monomer
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polynucleotide strands |
form by dehydration synthesis backbone of strand: regular alternation of sugars and phosphate groups does not carry info has a sequence of bases strand is polar 5' end and 3' end when DNA or RNA polymer is created, bond formed between 3' -OH group and 5' phosphate group
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DNA |
pentose sugar: deoxyribose nitrogenous bases: -purine: adenine, guanine -pyrimidine: thymine, cytosine pairing up of bases: A and T, C and G double helix -2 polynucleotides wrapped around each other -held together by H bonds between paired bases and van der waals reactions between stacked bases strands are antiparallel |
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RNA |
pentose sugar: ribose nitrogenous base: -purine: adenine, guanine -pyrimidine: uracil, cytosine |
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cell theory |
all living things are composed of cells and the products of cells cell is functional unit of life - level of organization at which property of life emerges all cells come only from pre existing cells by cell division |
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magnification |
ratio of an objects size to its real size increase in the apparent size of an object |
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resolving power |
minimum distance two points can be separated and still distinguised as two separate points measure of clarity of an image human eye: 0.1-0.2 mm light microscope: 0.2 micrometres electron microscopes: 2 nanometres |
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microscopes |
TEM: reveals internal details SEM: reveals surface details
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size ranges |
prokaryotic cells: 1-10 micrometres, some go down to .2 micrometres eukaryotic cells: 10-100 micrometres |
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cell size |
surface area/volume ratio -determines how fast materials can diffuse in and out of the cell; the ratio and the rate of diffusion fall as the cell gets larger time of diffusion is proportional to distance squared limited products from one nucleus cells can be very large if they are not spherical and/or are not active -motor neurons a meter long -chicken eggs before fertilization |
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prokaryotic cells |
small and simple pro = before, karyon = nucleus typically 1-5 micrometres long lack nucleus ribosomes and cell wall differ from those of eukaryotes capsule; sticky outer coat fimbriae; projections
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eukaryotes |
animals, plants, fungi, protists cells contain membrane bound organelles and non-membranous structures organelles -cellular metabolism occurs within organelles -nucleus, golgi, mito, ER -increase membrane area nonmembranous structures -cytoskeleton, centriole, flagellum most cells are small - large surface area to volume ratio
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the nucleus |
often the largest organelle stores, protects, replicates and expresses genetic info
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nuclear envelope |
double membrane space between membranes = perinuclear space nuclear pore complexes in the membrane; transmit traffic between the nucleoplasm and the cytosol |
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nucleoplasm |
contains chromatin and one or more nuclei (ribosome synthesis)
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chromatin |
DNA and proteins |
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nuclear lamina |
gives shape to nucleus consists of proteins called lamins (intermediate filaments) contains chromosome attachment sites for organizing the nuclear contents |
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nuclear matrix |
framework of fibres |
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ribosomes |
one of the required components necessary for protein synthesis two subunits, composed of proteins and rRNA not aurrounded by membrane 1000s to 1,000,000s per cell may be free (in cytosol) or bound (to ER) |
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eukaryotic ribosomes |
about 4 dozen proteins and four rRNA molecules molecular weight = almost 3 million dalton |
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free ribosomes |
located in cytosol make proteins that will be active in: -cytosol, chloroplast, mito, nucleoplasm, peroxisomes? |
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bound ribosomes |
bound to ER make proteins that will be active in: -endomembrane system (transmembrane proteins, proteins entirely within endomembrane system organelles) -extracellular areas (secreted proteins) |
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the endomembrane system |
a system of membranes whose members are in direct contact with one another or which engage in vesicular traffic with one another part of the system: -nuclear envolope, ER, golgi, vesicles, lysosomes, vacuoles, plasma membrane not part of the system: -peroxisomes, chloroplasts, mito |
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endoplasmic reticulum |
the ER is a network of tubes an sacs interior space = lumen or cisternal space |
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smooth ER |
lacks bound ribosomes functions: -lipis synthesis (phospholipids > membrane biogenesis, steroids > sex hormones, oils > sent to skin oil glands) -carbohydrate metabolism (last step of breakdown of glycogen to glucose) -sequesters Ca2+ -detoxifies many drugs and poisons |
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rough ER |
has bound ribosomes functions: -protein synthesis (for secretion, packaging into organelles, insertion into membranes) -protein sorting -protein modification (beginning with glycosylation) -membrane biogenesis, phospholipid synthesis |
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golgi apparatus |
also called dictyosome series of flattened sacs and associated vesicles consists of cis and trans cisternae: -cis golgi network (CGN): receiving, convex -trans golgi network (TGN): shipping, concave functions: -protein sorting, protein processing, addition and mod of oligosaccharides to glygoproteins and glycolipids, biogenesis of lysosomes (and secretory vesicles and vacuoles) |
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vesicles |
transport substances from one part of the endomembrane system to another > arise as part of the endomembrane system motor proteins (dyneins, kinesins) move vesicles along microtubule tracks |
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lysosomes |
compartment in animal cells that contain acid hydrolases: -glycosidases, lipases, phospholipases, proteases, nucleases, phosphatases maintain an acidic pH (5) -low pH: maintained by activity of an H+-ATPase in the lysosomal membrane (cytosolic pH: about 7.2) |
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heterophagy |
phagocytosis digestion of material brought into the cell from the environment related to lysosome pH |
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autophagy |
digestion of the cells own materials (worn out organelles) used during apoptosis, or programmed cell death related to lysosome pH |
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vacuoles |
central vacuole food vacuole contractile vacuole
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central vacuole |
quite large, occupying most of the volume in mature plant cells and many fungal cells functions: -occupies space (main function; holds water and provides cheap growth to plant) -performs hydrolytic functions, like lysosomes in animal cells -important in maintaining turgor pressure -stores various substances (wastes, toxins, pigments) |
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food vacuole and contracile vacuole |
in paramecium |
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mitochondria |
sites of cellular respiration; perform most of the oxidations that provide energy in the form of ATP for the cell 100s to 1000s per cell double membrane inner mitochondrial membrane -infoldings = cristae -site of the electron transport chain circular DNA (exceptions in highed plants - linear and circular) multiply by binary fission incapable of independent existence prokaryotic origin
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mitochondrial matrix |
site of the Krebs cycles (citric acid cycle) |
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chloroplasts |
types of plastids that perform photosynthesis in plants and algae green due to chlorophyll 1 to 100s in cell double membrane thylakoids may be stacked (>grana) circular DNS (exceptions for arabidopsis which has no chloroplast DNA in mature cells) multiply by binary fission incapable of independent existence prokaryotic origin |
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thykaloid membrane |
site of absorption site of light induced electron transport that produces ATP and NADPH for the calvin cycle part of a chloroplast |
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stroma |
site of calvin cycle, CO2 fixation part of chloroplast |
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chemiosmosis |
both mito and chloroplasts use electron transport chains to create an electrochemical gradient of protons that is used to make ATP
energy coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as ATP synthesis |
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endosymbiotic theory |
chloroplasts and mitochondria arose 2 billion years ago from bacteria that were engulfed by early eukaryotic cells |
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peroxisomes |
belong to a group of organelles collectively called microbodies single membrane are involved in various catabolic oxidative processed that remove hydrogen (strip electrons, e-) from organic molecules and transfer that hydrogen (those e-) to O2, forming H2O2 (hydrogen peroxide) as a by product (RH2 + O2 > R H2O2) also involved in oxidation of fatty acids, detoxification of poisons can split in two not part of the endomembrane system may have arisen from prokaryotic endosymbionts, but do not contain their own DNA |
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cytoskeleton |
bones and muscles extensive, dynamic network of protein filaments and associated proteins in eukaryotic cells
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cytoskeleton functions |
functions (support, organization, motility): -maintains and changes cell shape -holds organelles in position -transmits signals from cell surface to cell interior -forms tracks for movement of organelles -cell motility; cilia, flagella
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cytoskeleton components |
all made of proteins microtubules microfilaments intermediate filaments |
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microtubules |
tubulin heterodimers hollow fibers 25nm dynamic: can polymerize, depolymerize, or remain stable
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microtubule organizing centres (MTOC) |
nucleation sites for MT polymerization centrosome organizes the cystolic MTs and the spindle apparatus centriole (basal body) at the base of cilia and flagella centrioles of centrosome are not essential |
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motor proteins associated with MTs |
dyneins and kinesins walk along MTs in an ATP dependent manner motion can generate sliding effects between adjacent MTs motion of cilia and flagella based on sliding effects caused by dyneins walking along MTs motion can also carry cargo along MTs dyneins generally move their cargo toward the cell centre, kinesins move away from cell centre |
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microfilaments |
polymerized actin molecules solid rods of 7nm diameter associated motor proteins = myosins wide variety of structural and motile roles |
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microfilament roles |
structural support of cells and cell extensions in the sarcomere: -thin filaments are actin filaments -thick filaments are myosin filaments ATP dependent myosin walking action cell crawling: -plasmasol - plasmagel transformations -amoeboid movement; actin-myosin interactions near trailing end cytolosis/cytosplasmic streaming |
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intermediate filaments |
diverse group of filaments 8-12 nm diameter tough, durable fibers involved in support function only high tensile strength helps cells withstand mechanical stress (stretching) extensive network in cytosol form nuclear lamina that lines the nucleoplasmic face of the nuclear envelope some connected to desmosomes and hemidesmosomes |
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plant cell walls |
cellulose microfibrils in the marix of other polysaccharides and proteins functions: -protection -maintenance of shape -prevention of excess water uptake plasmodesmataare often present |
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animal cell surface |
intercellular junctions extracellular matrix hemidesmosomes (not an intercellular junctions); connections with intermediate filaments and ECM |
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intercellular junctions |
tight junctions: diffusing barrier desmosomes: anchoring junctions gap junctions: communication junctions
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extracellular matrix |
glycoproteins (collagens), proteoglycans, and other proteins cross linked to one another by extracellular adhesion proteins linked to the plasma membrane via cell adhesion molecules (CAMs, integrins) |
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extracellular matrix functions |
anchorage support tissue formation gene expression |
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components of membranes |
lipids -phospholglycerides -spongolipids -sterols proteins -peripheral -integral carbs -mono, di, and olgiosaccharide components of glycoproteins, glycolipids |
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functions of membranes |
selectively permeable compartmentalization of function energy transduction -inner mitochondrial membrane -chloroplast thylakoid -bacterial plasma membrane transport: proteins do the transporting -solutes -water: aquaporins site of enzymatic activity communication -signal transduction (hormone receptors in plasma mem) -cell-cell recognition (glycoprotein ID tags) -intercellular joining (gap junctions, tight junctions) -anchorage (to the cytoskeleton and the ECM) |
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fluid mosaic model of membranes |
membrane components and functions are asymmetric membrane fluidity -movement of membrane components -importance of membrane fluidity -factors affecting membrane fluidity |
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membrane components and functions are asymmetric |
the e face (exterior) is the external face; the p face is the internal face |
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movement of membrane components |
membrane phospholipids can exhibit four types of motion -lateral movement -rotation -flexing of fatty acid chains -flip flop transverse diffusion (undertaken by enzymes called flipases) membrane proteins move more slowly, but (at least some) can move laterally
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importance of membrane fluidity |
membranes must be fluid for basic cell processes to occur -cilia and flagella activity -phagocytosis -endocytosis/exocytosis -cell movement (amoeboid, euglenoid) -rates of simple diffusion -transport rates when membranes are too fluid -loss of structural organization and mechanical support; membranes leak when membranes are too rigid -mobility is poor; membranes leak
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factors affecting membrane fluidity |
temperature -lower > up membrane viscosity, down membrane fluidity -higher > up membrane fluidity, down membrane viscosity lipid composition -longer fatty acid chain length favours lower fluidity (more intermolecular contacts) -saturated fatty acid chains favours lower fluidity (more intermolecular contacts) -cis vs trans configuration (trans favours lower fluidity; more intermolecular contacts) -presence of sterols (cholesterol) |
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permeability characteristics of phospholipid bilayers and cellular membranes |
phopholipid bilayers (lacking transport proteins) are selectively permeable - they allow water to cross but not all solutes selective permeability of cellular membranes depends on discriminating barrier of phospholipid bilayer and the presence of transport proteins hydrophobic molecules - CO2, O2, N2, steroid hormones; pass right through < simple diffusion small uncharged polar molecules -H20, urea, ethanol, glycerol; some resistance, transport proteins help them cross large uncharged polar molecules -glucose, sucrose, nucleosides; large resistance, transport proteins required inorganic ions and organic ions -H+, Na+, Ca2+, Cl- and amino acids, nucleotides; large resistance, transport proteins required |
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passive transport |
diffusion of a substance across a membrane with no energy investment |
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diffusion |
spontaneous movement of particles of any kind from where they are more concentrated to where they are less concentrated dispersion of atoms, molecules, or ions as a result of random thermal motion from [higher] to [lower] > substances move down [] gradient |
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concentration gradient |
increase or decrease in the density of a chemical substance in an area difference in solute concn across a membrane or between two difference regions of a solution |
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osmosis |
simple diffusion of free water across a selectively permeable membrane solute decreases water's ability to move by osmosis |
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molarity |
# of moles of solute per liter (L) of solution 1 M substance = MW of substance in grams/L
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mole |
number of grams of a substance that equals its molecular weight in daltons and contains Avagadros number (6.02 X 10^23) of molecules |
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osmolarity |
# of osmoles of a substance per liter of solution (osm/L or osM) concentration of osmotically active particles in solution solute concentration expressed as molarity (osm/L = moles of solute/L) |
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osmole |
amount of a substance that results in avagadros number of particles when placed in solution, and which reduces the solvents freezing point by 1.86K |
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osmotic pressure |
a measure of the tendency of a solution to take up water when separated from pure water by a selectively permeable membrane; the greater the osmolarity, the greater the osmotic pressure =the amount of pressure that will just stop the flow by definition, the osmotic pressure of pure water is 0 |
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tonicity |
ability of a solution to cause a cell within it to gain or lose water takes into account non penetrating [solute] and membrane permeability |
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isoosmotic |
with medium fluids = same osmotic pressure as medium |
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isotonic |
having the same solute concentration as another solution |
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hyperosmotic |
compared to medium osmotic concentration lower than medium
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hypertonic |
in comparing 2 solutions, the one with the greater [solute] |
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hypoosmotic |
compared to medium osmotic concentration lower than medium |
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hypotonic |
in comparing 2 solution, the one with the lower [solute] |
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facilitated diffusion |
passive transport mediated by channel proteins and carrier proteins |
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channel proteins |
possess a hydrophilic channel through which atomic ions and some small molecules can pass some are open all the time others are gated -ligand gated -voltage gated -mechanically gated |
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carrier proteins |
undergo a shape change which takes small ions or molecules across direction of net solute transport is downhill conformation change in the carrier is independent of solute binding |
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active transport |
movement of a substance across a membrane, through a transport protein, against a chemical or electrochemical gradient requires input of energy can be powered by -ATP hydrolysis (Na+/K+ ATPase) -light absorption (bacteriorhodopsin -electron transport -cotransport with a substance moving down its gradient (secondary active transport) (symports and antiports, eg Na+ / glucose secondary active symport of gut epithelium) |
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exoocytosis |
vesicular removal of molecules to the extracellular fluid |
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constitutive exosytosis |
ubiquitous and continuous supplies proteins and lipids to the plasma membrane secretes many molecules from the cell |
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regulated exocytosis |
operates in cells specialized for secretion membrane fusion occurs only in response to an extracellular signal |
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membrane fusion |
when membranes fuse with each other, the orientation of the leaflets remains the same (pface still faces cytoplasm)
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endocytosis |
vesicular uptake of molecules from extracellular fluid |
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phagocytosis |
uptake of large, bulky material contractile activities of microfilaments and myosins cause phagocytic cells to engulf material with pseudopodia, then pinch off a vacuole within the cell used for -feeding (sponges) -defense (human macrophages and other phagocytes) endocytosis |
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pinocytosis |
non specific uptake of fluid from extracellular fluid occurs almost continuously in most cells helps control cell volume, SA endocytosis
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receptor mediated endocytosis |
uptake of specific molecules from extracellular fluid mediated by cell membrane receptors and cytosolic proteins coated vesicles are formed endocytosis |
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enzymes are proteins that catalyze biochemical reactions |
they lower activation energy of reactions, thereby making the reactions go faster they do not change the deltaG of a reaction |
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enzymes are specific to one (or a few) substrates |
substrate = substance that the enzyme works on |
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enzymes have active sites |
active site: small part of enzyme that binds to substrate induced fit: substrate binding causes a change in the shape of the active site |
