Lecture 14: Enzyme Regulation

Question 1

How are metabolic enzymes regulated?

Answer 1

compartmentalization: different locations
enzyme concentration: on/off switch
enzyme activity: volume control
hormone signals and second messengers: master regulators

Question 2

Substrate level control acts on a _____ reaction

Answer 2

single

Question 3

Feedback control targets a ________ in the pathway

Answer 3

different step

Question 4

Activators ____ more products

Answer 4

promote

Question 5

Inhibitors ____ more products

Answer 5

prevent

Question 6

What do isozymes do?

Answer 6

catalyze the same reaction but with different efficiencies

Question 7

What do reversible covalent modifications do?

Answer 7

add 1+ functional groups to activate/inactive the enzyme

Question 8

What is the donor molecule in phosphorylation modification?

Answer 8

ATP

Question 9

What is an example of a modified protein in phosphorylation modification?

Answer 9

glycogen phosphorylase

Question 10

Protein function of phosphorylation modification

Answer 10

glucose homeostasis; energy transduction

Question 11

Donor molecule of acetylation modification

Answer 11

acetyl CoA

Question 12

Example of modified protein in acetylation modification

Answer 12

histones

Question 13

protein function of acetylation modification

Answer 13

DNA packing; transcription

Question 14

Donor molecule of myristoylation modification

Answer 14

myristoyl CoA

Question 15

myristoylation modification example of modified protein

Answer 15

Src

Question 16

myristoylation modification protein function

Answer 16

signal transduction

Question 17

ADP ribosylation donor molecule

Answer 17

NAD+

Question 18

ADP ribosylation example of modified protein

Answer 18

RNA polymerase

Question 19

ADP ribosylation protein function

Answer 19

transcription

Question 20

Farnesylation modification donor molecule

Answer 20

farnesyl pyrophosphate

Question 21

Farnesylation modification example of modified protein

Answer 21

Ras

Question 22

Farnesylation modification protein function

Answer 22

signal transduction

Question 23

gamma- Carboxylation modification donor molecule

Answer 23

HCO3-

Question 24

gamma- Carboxylation modification example of modified protein

Answer 24

thrombin

Question 25

gamma- Carboxylation modification protein function

Answer 25

blood clotting

Question 26

Sulfation modification donor molecule

Answer 26

3'-phophoadenosine-5'-phophosulfate

Question 27

Sulfation modification example of modified protein

Answer 27

fibrinogen

Question 28

Sulfation modification protein function

Answer 28

blood clot formation

Question 29

ubiquitination modification donor molecule

Answer 29

ubiquitin

Question 30

ubiquitination modification example of modified protein

Answer 30

cyclin

Question 31

ubiquitination modification protein function

Answer 31

control of cell cycle

Question 32

Why is phosphorylation activating?

Answer 32

1. thermodynamics: ATP hydrolysis can drive unfavorable reactions 2. kinetics: physiological processes dictate reaction rate 3. cell processes: ATP amounts dictated by metabolism (energy charge), signal transduction amplification (catalytic turnover) 4. shape and charge complementarity: each phosphate adds (-2) charge and (3+) H-bonds

Question 33

Kinases _____ phosphates

Answer 33

ADD

Question 34

phosphatase ____ phosphates

Answer 34

REMOVE

Question 35

Allosteric binding does or does not occur at the active site?

Answer 35

does not

Question 36

Heteroallostery definition

Answer 36

effector binds at the allosteric site

Question 37

Homoallostery definiton

Answer 37

cooperatively

Question 38

Binding of CTP to ACTase prefers what site?

Answer 38

T/inactive site

Question 39

Binding of ATP prefers to ACTase prefers what site?

Answer 39

R/active site

Question 40

histone acetylation ______ transcription

Answer 40

promotes

Question 41

histone phosphorylation _____ transcription

Answer 41

prevents

Question 42

Histone methylation does what for transcription?

Answer 42

promotes or prevents