Chapter 22 (Glycogen Breakdown and Synthesis)

Question 1

When ___ breaks down glycogen it must stay within the cell

Answer 1

muscle

because Glucose-6P cannot cross the cell membrane

Question 2

When ___ breaks down glycogen it can go elsewhere throughout the body

Answer 2

liver

because the liver has Glucose-6-phosphatase

Question 3

Only glucose units that are at least ___ units away from a branch point are cleaved

Answer 3

5

Question 4

Glucose’s break off as

Answer 4

Glucose-1P

Then goes through phosphoglucomutase

Question 5

Glycogen Debranching enzyme

Answer 5

Creates and breaks alpha(1-4) bonds

Question 6

Phosphoglucomutase creates

Answer 6

A Glucose-1,6-BP intermediate

Question 7

UDP-Glucose Pyrophosphorylase

Answer 7

Turns Glucose-1P into UDP-Glucose
(transferes a UMP)
Requires UTP
Produces PPi (driving force behind the rxn)
Irreversible

Question 8

Glycogen Synthase

Answer 8

Attaches the Glucose in UDP-Glucose to a Glycogen (n+1) molecule
Requires Glycogen (n)
Produces a UDP
ONLY generates alpha(1-4) linkages yielding alpha-amylose

Question 9

Most glycosyl groups in mammals are donated by ___

Answer 9

UDP-Glucose

Question 10

In plants, starch is built from glucose units donated by ___

Answer 10

ADP-Glucose

Question 11

Glycogen Branching Enzyme

Answer 11

Transfers 7 residue segments from the end of a chain to the C6-OH group
Breaks alpha (1-4) bonds
Creates alpha (1-6) bonds

Question 12

Overall reaction for glycogen storage and utilization

Answer 12

Glucose + Pi + 2 NAD + ADP (arrow) 2 pyruvate + ATP + 2 NADH + H2O

Question 13

Storage costs ___ ATP and utilization gives us ___ ATP

Answer 13

2

3

Question 14

Internal cellular regulation is via ___ regulation

Answer 14

allosteric

Question 15

High demand for ATP

Answer 15

Glycogen synthase is inhibited

Question 16

Low demand for ATP

Answer 16

Glycogen synthase is favored

Question 17

Regulation between cells occurs via ___

Answer 17

Hormones

insulin,glucagon,epinephrine

Question 18

Difference between glucagon and epinephrine

Answer 18

Glucagon: long-term maintenance
activates liver gluconeogenesis
act in the LIVER and ADIPOSE only

Epinephrine: fight or flight
acts on LIVER and MUSCLE

Question 19

Active form (A) of:
Glycogen synthase
Glycogen phosphorylase

Answer 19

dephosphorylated (-OH)

phosphorylated (-OPO3)

Question 20

Glycogen phosphorylase regulation (allosteric)

Answer 20

Activator: AMP
Inhibitor: ATP, G6P, and glucose (in liver)

Question 21

Glycogen synthase regulation (allosteric)

Answer 21

Activator: G6P

Question 22

Least active form of enzyme

Answer 22

Tb

Question 23

Most active form of enzyme

Answer 23

Ra

Question 24

Insulin dephosphorylation (on/off)

Answer 24

Glycogen synthase: on
Phosphorylase kinase: off
Glycogen phosphorylase: off

Question 25

Epinephrine/Glucagon phosphorylation (on/off)

Answer 25

Turns ATP to cAMP Protein Kinase A (PKA): on Phosphorylase kinase: on Glycogen phosphorylase: on

Question 26

Binding of epinephrine and glucagon activates a heterotrimeric ___ protein

Answer 26

G | Inactive when bound to GDP

Question 27

Creation of cAMP

Answer 27

epinephrine/glucagon bind to G protein GDP becomes GTP Causes the dissociation of alpha and beta, gamma subunits Dissociated subunits can activate/inactivate other cellular components

Question 28

Off switch to GTP

Answer 28

Alpha subunit is a GTPase that hydrolyzes GTP to GDP + Pi | Becomes inactive

Question 29

Adenylate Cyclase

Answer 29

Turns ATP into cAMP | Produces PPi

Question 30

Phosphodiesterase

Answer 30

Turns cAMP into AMP Requires H2O Caffeine inhibits this enzyme increase the lifetime of cAMP

Question 31

Protein Kinase A (PKA) is activated by the binding of ___

Answer 31

cAMP

Question 32

Phosphorylation cascade

Answer 32

cAMP activates Protein Kinase A (PKA) PKA phosphorylates Phosphorylase Kinase and phosphorylates Glycogen Synthase (inactive) Phosphorylase Kinase activates Glycogen Phosphorylase

Question 33

Muscle Phosphorylase Kinase is allosterically activated by ___

Answer 33

Calcium | Binding subunit is called calmodulin

Question 34

PP1 is a ___ regulator

Answer 34

Covalent modification

Question 35

___ allosterically activates dephosphorylated glycogen synthase

Answer 35

G-6P