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Biochemistry Exam 1 > Chapter 22 (Glycogen Breakdown and Synthesis) > Flashcards

Chapter 22 (Glycogen Breakdown and Synthesis) Flashcards

1
Q

When ___ breaks down glycogen it must stay within the cell

A

muscle

because Glucose-6P cannot cross the cell membrane

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2
Q

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

A

liver

because the liver has Glucose-6-phosphatase

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3
Q

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

A

5

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4
Q

Glucose’s break off as

A

Glucose-1P

Then goes through phosphoglucomutase

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5
Q

Glycogen Debranching enzyme

A

Creates and breaks alpha(1-4) bonds

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6
Q

Phosphoglucomutase creates

A

A Glucose-1,6-BP intermediate

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7
Q

UDP-Glucose Pyrophosphorylase

A 
Turns Glucose-1P into UDP-Glucose
(transferes a UMP)
Requires UTP
Produces PPi (driving force behind the rxn)
Irreversible
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8
Q

Glycogen Synthase

A

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

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9
Q

Most glycosyl groups in mammals are donated by ___

A

UDP-Glucose

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10
Q

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

A

ADP-Glucose

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11
Q

Glycogen Branching Enzyme

A 
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
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12
Q

Overall reaction for glycogen storage and utilization

A

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

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13
Q

Storage costs ___ ATP and utilization gives us ___ ATP

A

2

3

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14
Q

Internal cellular regulation is via ___ regulation

A

allosteric

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15
Q

High demand for ATP

A

Glycogen synthase is inhibited

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16
Q

Low demand for ATP

A

Glycogen synthase is favored

17
Q

Regulation between cells occurs via ___

A

Hormones

insulin,glucagon,epinephrine

18
Q

Difference between glucagon and epinephrine

A

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

Epinephrine: fight or flight
acts on LIVER and MUSCLE

19
Q

Active form (A) of:
Glycogen synthase
Glycogen phosphorylase

A

dephosphorylated (-OH)

phosphorylated (-OPO3)

20
Q

Glycogen phosphorylase regulation (allosteric)

A

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

21
Q

Glycogen synthase regulation (allosteric)

A

Activator: G6P

22
Q

Least active form of enzyme

A

Tb

23
Q

Most active form of enzyme

A

Ra

24
Q

Insulin dephosphorylation (on/off)

A

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

25
Q

Epinephrine/Glucagon phosphorylation (on/off)

A

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

26
Q

Binding of epinephrine and glucagon activates a heterotrimeric ___ protein

A

G

Inactive when bound to GDP

27
Q

Creation of cAMP

A

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

28
Q

Off switch to GTP

A

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

Becomes inactive

29
Q

Adenylate Cyclase

A

Turns ATP into cAMP

Produces PPi

30
Q

Phosphodiesterase

A

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

31
Q

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

A

cAMP

32
Q

Phosphorylation cascade

A

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

33
Q

Muscle Phosphorylase Kinase is allosterically activated by ___

A

Calcium

Binding subunit is called calmodulin

34
Q

PP1 is a ___ regulator

A

Covalent modification

35
Q

___ allosterically activates dephosphorylated glycogen synthase

A

G-6P

Biochemistry Exam 1 (8 decks)

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