Question | Answer |
What is a buffer? | conjugate acid-base pair that prevents or minimizes changes in pH with the addition of small amounts of acid or base substances |
Define pH? | physical property of a solution determined by conjugate acid/base pair at equilibrium |
The depletion of H+ ________ pH. | increases |
What happens when you add an acid to a system? | the base reacts with the H+ and the equilibrium shifts to acid |
What happens when you add a base to a system? | the acid reacts with the OH- and the equilibrium shifts to base |
What is the equation to calculate pH? | pH=pKa+log [conjugate base]/[conjugate acid] |
Why are buffers important? | they are important for maintaining homeostasis |
What is the pH of human plasma? | 7.35-7.45 |
How is human plasma pH maintained? | by weak salts, acids as conjugate pairs, bicarbonate system, phosphate buffering system |
What is acidosis? | pH below 7.35 |
What is alkalosis? | pH above 7.45 |
What is an enzyme made of? | proteins which are made of amino acids with ionizable groups |
What is a zwitterion? | ionic form of amino acids at pH 7 |
When are ionic groups of proteins lost? | when peptide bonds are formed |
What makes an amino acid basic or acidic? | containing an additional ionizable group |
What is crutial to enzyme function? | the ionizable groups becuase they allow the protein chains to be linked or confromed in a particular shape |
Define: enzyme | biocatalytic protein; most efficient catalysts known |
What are 3 unique features of enzymes? | Efficiency, specificity, and regulation |
define: efficiency (in terms of enzymes) | enzymes can catalyze a reaction almost immediately |
What is an example of enzyme efficiency? | enzyme cholinesterase: breaks down acetyle choline almost immediately for muscle contractions |
What is specificity? (in terms of enzymes)? | most enzymes exhibit relative specificity i.e. catalyze the same type of reaction with realitively similar structured substances |
What is an example of enzyme specificity? | enzyme monoaminoxidase: catalyzes norepinphrine, serotonin, dopamine |
What type of regulation do most enzymes use? | allosteric regulation |
What is allosteric regulation? | enzymes bind on some region of the enzyme to alter active site so S is not recognized or enhavces the function |
What are the two types of specificity? | Relative specificity and absolute specificity |
What is relative specificity? | enzymes catalyze the same types of reactions with similar structured substances |
What is absolute specificity? | enzymes catalyze only one type of reaction with a specific substrate |
What is an example of an enzyme that uses absolute specificity? | glycerol kinase |
Define: active site (in terms of enzymes) | region of an enzyme that recognizes a given substrate and catalyzes the conversion of a substrate to a product |
What happens to an enzyme during catalysis reactions? | the reaction will start and end with the enzyme i.e. neither created nor destroyed |
What are the 3 types of reactions at the active site? | bond-strain catalysis, acid-base catalysis, and orientation catalysis |
What is bond strain catalysis? | S binds to enzyme which causes bond strain and increases the probability that the bond will break |
What is acid-base catalysis? | active site has an ionizable r-group and they interact as proton donors or acceptors |
what is orientation catalysis? | substrate is held in an orientation that optimizes/maximizes the probability of a reaction |
What role does temperature play in reaction rates? | higher temperatures may increase reaction rates |
What happens to enzymatic reaction rates at low temperatues? | at low temperatures the enzyme is cold inactiavated |
In cold inactivated enzymes, the inactivation is ______. | reversible |
What happens to intermediate to high temperatures on enzymatic reactions? | as the temperature increases, the conversion from S-P increases due to increase in kinetic activity |
What hapens to enzymatic reaction rates at extremely high temperatures? | enzyme activity completely stops because the enzyme is denatured |
In high temperature inactivated enzymes, the inacivation is _______. | irriversible |
What role does pH play in enzymatic reactions? | most reactions have an optimum pH at which the reaction rate is at it's most efficient |
What does altering pH from optimum do? | effects the ionizable groups of amino acids that will make up the enzyme i.e. affect confirmation and alter recognition of the substrate |
What do many enzymes depend on for optimum activity or presence of activity? | cofactors |
What are cofactors? | non-protein substance |
What is an enzyme in the absens of a cofactor/ with low or no activity? | apoenzyme |
What is an enzyme in the presence of a cofactor? | haloenzyme |
What are the two categories of cofactors? | inorganic and organic |
What are inorganic cofactors? | usually ions, Zn2+,Mg2+,Fe2+, Ca2+ |
What are organic cofactors? | often derived from vitamins, NAD+ |
What are organic cofactors often called? | coenzymes |
Define: vitamins | essential nutrients not derived endogenously |
What are fat soluble vitamins? | A,E,D |
What are water soluble vitamins? | B series |
How many role sdo cofactors have? | 2 |
What is the first role of cofactors? | alter substrate or enzyme conformation to maximize interaction |
What is the second role of cofactors? | participate in reaction as a second substrate by doating or accepting a particular chemical grouping |
Enzymes can be ______ by both physiological and pharmacological agents | inhibited |
What are the two types of pharmacological enzyme inhibitors? | irreversible inhibitors and reversible inhibitors |
What are irriversible inhibitors? | inhibitors that bind to the active site and are not released |
What is an example of an irriveresible inhibitor? | organophosphate nerve gas |
How do orgnaophosphate nerve gases work? | blocks the reaction |
What are reversible inhibitors? | inhibitors that may be removed |
What are the two types of reversible inhibitors? | competitive inhibitors and noncompetitive inhibitors |
What are competitive inhibitors? | reversible inhibitors that bind to the active site, but can be displaced in the presence of high substrate concentrations |
What are noncompetitive inhibitors? | reversible inhibitors that bind the enzyme outside of the active site and cause an allosteric or conformational change that alters active sites |
How are noncompetitive inhibitors reversed? | they are reversed as the inhibitor is released and degrated |