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Physiology Quiz 1
3.8, 3.12, 4.1, 4.2
| Question | Answer |
|---|---|
| typical life of a protein | a few days |
| a _____ protein is more readily degraded than ______ protein | degraded ; intact |
| what causes a protein to be degraded very quickly? | chemical or physical damage |
| ubiquitin | targets protein for degradation (attachment of peptide), sends to proteasome |
| proteasome | large protein complex that breaks protein up into individual amino acids and recycles it |
| ligand | any molecule that is bound to and affects a protein by either electrical attractions or weaker attractions due to hydrophobic forces |
| binding site | the region of a protein where a ligand binds |
| what does the binding of a ligand do to a protein? | it changes the conformation of protein (either activates it or inhibits it) |
| the closer the surface of ligand and binding site... | the stronger the attraction |
| for a ligand to be able to bind to a protein.. | it has to be close to the protein |
| what is a ligand's binding ability based on? | shape structure chemical composition |
| chemical specificity | CAN IT BIND allows protein to identify one particular ligand |
| what does chemical specificity depend on? | the shape of binding site |
| molecules that are less specific can.. | bind a number of related proteins |
| the less specific a mlx is... | the more types of proteins that can bind |
| what determines the side effects of drugs? | the degree of specificity |
| affinity | WILL IT BIND & STAY BOUND the STRENGTH of the ligand-protein binding |
| what determines how likely it is that a bound ligand will leave the protein surface and return to its unbound state? | affinity |
| different proteins can have the same_______ for a ligand but have different _____ for that same ligand | chemical specificity ; affinity |
| when there is high affinity... | very little of the ligand is needed to bind to the protein |
| saturation | the fraction of total binding sites that are occupied at any given time |
| all binding sites are occupied | 100% saturation |
| half the binding sites are occupied | 50% saturation |
| % saturation depends on | 1. the concentration of unbound ligand in the solution 2. the affinity of the binding site for the ligand |
| the greater the ligand concentration... | the more likely it is a ligand enters a binding site and binds |
| even if specificity is low, what can drive binding? | a high concentration |
| competition | when more than one type of ligand can potentially bind to a certain binding site |
| allosteric modulation | when a protein has two binding sites and the binding of a ligand to one of the sites alters the shape and activity of the other site |
| functional (active) site | carries out the protein's physiological function |
| regulatory site | where the modulator mlx binds, modifies shape and activity |
| what happens to a modulator in allosteric modulation? | once it binds and activates, it leaves/falls off |
| covalent modulation | covalent bonding of charged chemical groups to a protein |
| most common type of covalent modulation | adding a phosphate group to hydroxyl |
| is covalent modulation permanent or reversible? | it is permanent unless phosphoprotein phosphatase cuts the phosphate group off |
| what does adding or removing a phosphate group require? | enzymes |
| kinase | enzyme that ADDS the phosphate group to a protein |
| phosphatase | enzyme that REMOVES the phosphate group from a protein |
| the rates of enzyme-mediated runs can be increased by.. | increasing temp increasing substrate concentration increasing enzyme activity increasing enzyme concentration |
| maximal saturation | when the active binding site of every enzyme is occupied by a substrate |
| what happens when the substrate concentration is too high concerning glucose in the kidney? | when glucose is too high, it will end up in urine, because the kidneys could not reabsorb |
| if there is twice as much enzymes.. | the saturation point is twice as high |
| in order to change concentration of an enzyme... | you must change the rate of enzyme synthesis or breakdown at the DNA level |
| first characteristics of enzymes | 1. does NOT undergo a chemical change as a consequence of the reaction that it catalyzes |
| second characteristic of enzymes | binding of substrate to enzyme's active site is the same as ligand binding to a protein |
| third characteristic of enzymes | enzyme increases rate of chemical reaction but doesn't cause a reaction to occur that wouldn't occur in its absence |
| fourth characteristic of enzymes | does not change chemical equilibrium, it only increases the RATE at which equilibrium is achieved |
| co-factor | helps binding and protein shape but does not participate in reaction |
| what type of mlx are co-factors? | METALS |
| example of co-factor | iron helps O2 bind allows hemoglobin to go from oxygenated state to deoxygenated state |
| co-enzyme | plays MAJOR role and participates DIRECTLY in reaction |
| what type of mlx are co-enzymes? | ORGANIC MLX (have carbons as part of their structure) |
| example of co-enzyme | B vitamins NAD+, binds to alcohol mlx and helps them break down |
| fat-soluble vitamins | A,D,E,K the only vitamins that will cause overdose |
| simple diffusion | movement of mlx from one location to another bc of random thermal motion requires no energy or heat |
| does simple diffusion require ATP? | no |
| example of simple diffusion | oxygen, nutrients, and other mlx entering capillaries |
| which way do mlx move in simple diffusion | down their concentration gradient |
| diffusion will speed up as... | increase temperature increase magnitude of difference in solute concentration from one side to another |
| flux | the amount of material crossing a surface in a unit of time |
| diffusion equilibrium | fluxes are equal in magnitude but opposite in direction net flux = 0 |
| magnitude of flux depends on | -temp -mass of mlx -surface area -medium the mlx are traveling through |
| what is the major limiting factor of membranes | its chemical composition |
| polar molecules | diffuse into cells slowly or not at all |
| examples of polar molecules | H2O, Na+, K+, proteins |
| non-polar mlx | will diffuse easily because they have large permeability coefficients can dissolve in non polar regions of membrane occupied by the fatty acid chains of phospholipids |
| example of non-polar mlx | O2, CO2, fatty acids, steroid hormones |
| ion channel | allows ions to diffuse across the membrane |
| ion channels have selectivity based on... | - channel diameter - charged surface of subunits - # of water mlx associated with ions |
| channel gating | process of opening/ closing ion channels can occur many times each second |
| ligand-gated ion channel | binding of a ligand results in opening of the channel |
| mechanically-gated ion channels | open in response to physical deformation (like pressure) of receptor |
| voltage-gated ion channels | opened by change in voltage (electrochemical potential) conduct ions accounting to electrochemical gradient |
| one function of membrane transport proteins | maintaining membrane potential and electrochemical gradient |
| what is the charge inside of the cell? | slight negative charge |
| is the cell chemically balanced? | no |
| where do the opposite charges align? | on the surface of plasma membrane |
| transporters | integral membrane proteins mediate the passage of large/polar molecules |
| mediated transport | movement of substances through the membrane |
| factors that determine the magnitude of solute flux in mediated-transport system | solute concentration affinity of transporters for solute # of transporters in membrane rate of conformational change |
| two types of mediated transport | facilitated diffusion and active transport |
| facilitated diffusion | net flux of a molecule across a membrane always proceeds from HIGH to LOW concentration *uses a transporter to move solute contributes significantly to metabolic homeostasis |
| active transport | used to move substances 'uphill' against the concentration gradient referred to as pumps DIRECT USE OF ATP |
| two types of active transport | primary and secondary active transport |
| primary active transport | hydrolysis of ATP by a transport, directly relies on ATP |
| example of primary active transport | Na+ / K+ ATPase pump |
| concentration of Na+/K+ IN cell | Na+ 15 mM K+ 150 mM |
| concentration of Na/K+ OUTSIDE cell | Na+ 145 mM K+ 5 mM |
| secondary active transport | movement of an ion down its electrochemical gradient is coupled to the transport of another mlx INDIRECTLY uses ATP |
| two binding sites of transporters in secondary active | one for ion (normally Na+) another for second substrate (ex: amino acid, vitamin) |
| the movement of Na+ is always in what direction? | high to low |
| how does secondary active transport use ATP? | indirectly uses stored energy in the ion to get the substrate into cell because it is moving against its concentration gradient |
| cotransport | movement of actively transported solute into cell (same direction as Na+) |
| countertransport | movement of actively transported solute OUT of cell (opposite of Na+) |
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thomask9
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