Review 3: Gluconeogenesis

Question 1

True or false: Hepatic and muscle glycogen serve the same role

Answer 1

false

Question 2

What hormone stimulations glycogen production?

Answer 2

insulin

Question 3

What hormone stimulates glycogen breakdown?

Answer 3

glucagon

Question 4

Walk through the process of glycogen formation after a meal

Answer 4

GLUT4 transporter takes glucose up into the blood (stimulated by insulin) —> glucose is converted to gluc 6-phosphate —> glycolysis or glycogen

Question 5

During exercise, glycogen breakdown is stimulated by ___________

Answer 5

epinephrine (or muscle contraction)

Question 6

What 3 second messenger systems activate glycogen phosphorylase?

Answer 6

1) cAMP
2) PI
3) Ca++

Question 7

What two extracellular stimuli can turn those secondary messengers on?

Answer 7

1) glucagon

2) epinephrine

Question 8

How does insulin prevent glycogenolysis?

Answer 8

by inhibiting glycogen phosphorylase by causing the enzyme to be dephosphorylated and inactivated

Question 9

Glycogen synthase is ACTIVE when it is _____________

Answer 9

dephosphorylated

Question 10

Glycogen synthase is INHIBITED when it is ___________

Answer 10

phosphorylated

Question 11

Glycogen phosphorylase is ACTIVE when it is ______________

Answer 11

phosphorylated (breaks down glycogen)

Question 12

Glycogen phosphorylase is INHIBITED when it is ______________

Answer 12

dephosphorylated

Question 13

What 2 enzymes are responsible for breaking down Glycogen?

Answer 13

1) Glycogen phosphorylase

2) Debranching enzyme

Question 14

What 2 enzymes are responsible for synthesizing Glycogen?

Answer 14

1) Glycogen synthase

2) Branching enzyme

Question 15

What is the monomer from the breakdown of glycogen?

Answer 15

glucose 1-phosphate

Question 16

What is the monomer used to synthesize glycogen?

Answer 16

UDP-glucose

Question 17

What intermediate is capable of binding to phosphorylase b (the dephosphorylated inactive form) and making it active?

Answer 17

AMP

Question 18

What two things can bind to phosphorylase a (phosphorylated active) to cause INACTIVITY (no more breakdown of glycogen)

Answer 18

ATP and glucose

Question 19

Main point: Glycogen breakdown is ACTIVE when things (synthase or phosphorylase) are _____________

Answer 19

phosphorylated

Question 20

Glycogen synthesis is ACTIVE when things are ________________

Answer 20

dephosphorylated

Question 21

The inactive form of enzymes is the A or B form

Answer 21

B

Question 22

In certain pathological conidtions, high levels of glucose 6-phosphate can bind and cause a conformational change to allosterically _________ glycogen synthase b

Answer 22

activate

Question 23

phosphorylation promotes glycogen ___________

Answer 23

degradation

Question 24

dephosphorylation promotes glycogen ____________

Answer 24

storage and synthesis

Question 25

Defective enzyme in von Gierke’s disease

Answer 25

glucose 6-phosphatase

cannot break down glycogen – affects liver and kidney

Question 26

What is the defective enzyme in Pompe’s disease?

Answer 26

1,4 glucosidase

affects all organs

Question 27

Defective enzyme in Cori’s disease

Answer 27

amylo 1,6 debranching

(affects muscle and liver)

leads to more short outer glycogen fragments

Question 28

Defective enzyme in Anderson’s disease (IV)

Answer 28

branching enzyme

(affects liver and spleen)

leads to normal amounts of glycogen but longer branches

Question 29

Defective enzyme in McArdle’s disease

Answer 29

phosphorylase

affects muscle

Question 30

What 3 glycogen storage diseases affect the muscle?

Answer 30

amylo 1,6 branching (Cori’s disease), phosphorylase (McArdle’s), PFK-1 (VII)