Week 2

Question 1

vi

Answer 1

the initial rate of the reaction at a certain substrate concentration

Question 2

vmax

Answer 2

the maximal velocity a rxn can achieve at an infinite concentration of substrate

Question 3

Km

Answer 3

substrate concentration at which the rxn rate is at half-max and is a measure of the substrate’s affinity for the enzyme

Question 4

Michaelis-Menten Equation

Answer 4

vi = Vmax[S]/(Km+[S])

Question 5

rate of rxns can be influenced by

Answer 5

temperature

H+ ion centration

Question 6

competitive inhibitor

Answer 6

binds in the active site

Question 7

competitive inhibitor impact of Km

Answer 7

increases it - substrate concentration must increase to compete with inhibitor

Question 8

competitive inhibitor impact on Vmax

Answer 8

remains the same

Question 9

do competitive inhibitors speed up or slow down the enzyme rxn

Answer 9

slow down

Question 10

the impact of a competitive inhibitor can be overcome by

Answer 10

increase in substrate concentration

Question 11

noncompetitive inhibitor

Answer 11

binds in an alternative location to the active site

Question 12

impact of noncompetitive inhibitor on Vmax

Answer 12

Vmax decreased

Question 13

impact of noncompetitive inhibitor on Km

Answer 13

remains the same

Question 14

allosteric effectors

Answer 14

bind to sites that are not the active sites

Question 15

allosteric activators

Answer 15

positive effectors
enhance enzyme rxn
stabilize a conformation of the protein that increases substrate binding and rxn rate - Rstate

Question 16

allosteric inhibitors

Answer 16

negative effectors
inhibit enzyme rxn
stabilize a conformation of the protein that decreases binding of substrate and rxn rate

Question 17

phosphorylation by a kinase on…

Answer 17

the R groups of serine and tyrosine and sometimes threonine

Question 18

phosphorylations can…

Answer 18

• change protein comformation and activity

- change protein charge

Question 19

kinases phosphorylate

Answer 19

serine and threonine

Question 20

tyrosine kinases phosphorylate

Answer 20

tyrosine residues

Question 21

protein phosphatases

Answer 21

hydrolyze the phosphoester bonds of phosphorseryl and phosphortyrosyl residues

Question 22

methylation is typical in

Answer 22

c or g nucleotides

Question 23

increased histone acetylation will result in

Answer 23

decreased histone:DNA interaction allowing for transcriptional accessibility

Question 24

types of covalent modification

Answer 24

phosphorylation
hydrolyzation
methylation
acetylation

Question 25

pos delta G

Answer 25

rxn requires energy to take place

Question 26

neg delta G

Answer 26

reaction is spontaneous

Question 27

anabolic have pos or neg delta G

Answer 27

pos

Question 28

catabolic have pos or neg delta G

Answer 28

neg

Question 29

Phosphorylation of muscle glycogen phosphorylase is an example of

Answer 29

enzyme regulation through covalent modification

Question 30

activation of chymotrypsinogen to chymotrypsin is an example of

Answer 30

enzyme activation by cleavage

Question 31

The association of DNA and histones can be modified by histone acetylation. A decrease in histone acetylation will have what impact on the association of DNA and histones?

Answer 31

increase DNA: histone association

Question 32

no change in Km with the addition of the drug but change in Vmax could indicate the drug is

Answer 32

a noncompetitive inhibitor

Question 33

a drug that changes the Vmax without changing the Km has what impact on its target

Answer 33

reduces the catalytic activity of the enzyme

Question 34

A new enzyme is discovered that increases in activity when it is phosphorylated on an exposed tyrosine residue. Phosphorylation of this amino acid is classified as...

Answer 34

covalent modification

Question 35

change in Km with no change in vmax

Answer 35

competitive inhibitor

Question 36

As levels of B increase, this will decrease the conversion of S3 to B. This describes what type of regulation in a biosynthetic pathway?

Answer 36

feedback inhibition

Question 37

Children with cystinosis have growth delay and both renal and ocular issues due to accumulation of cysteine in cellular lysosomes. The defect involves a specific lysosomal membrane receptor that facilitates cysteine removal from the cell. An effective therapy has been administration of a drug with a similar structure to cysteine. This therapy reflects the general principle that competitive inhibitors typically resemble the structure of

Answer 37

substrates or ligands that bind the active site