MC + SHORT ANSWER ETC

Q: Compare insulin, glucagon, and epinephrine in glycogen regulation.

• Insulin promotes glycogenesis

• glucagon and epinephrine inhibit glycogenesis and favor mobilizing stored energy.

Q: What happens to glycogen synthase in response to insulin?

A: PP1 removes phosphate groups, activating glycogen synthase.

Q: After a carbohydrate-rich meal, which hormone predominates and what happens to glycogen synthesis?

A: Insulin rises, promoting glucose uptake and increasing glycogen synthesis.

Q: During low blood glucose, which hormone rises and what happens to glycogenesis?

A: Glucagon rises, particularly affecting the liver, and glycogenesis decreases.

Q: During physical exertion, which hormone rises and what happens to muscle glycogen?

A: Epinephrine rises and promotes muscle glycogen breakdown to help supply energy.

Q: Why is it useful for glycogenesis to be inhibited during exertion?

A: The body can prioritize mobilizing stored carbohydrate for immediate energy needs rather than storing more glucose.

Q: What is the key relationship between phosphorylation and glycogen synthase activity in these notes?

A: Dephosphorylation activates glycogen synthase; phosphorylation decreases its activity.

Q: What is the overall sequence of the four main glycogenesis steps?

A: Glucose → glucose-6-phosphate → glucose-1-phosphate → UDP-glucose → glycogen elongation.

Q: What is the difference between the roles of hexokinase, phosphoglucomutase, UDP-glucose pyrophosphorylase, and glycogen synthase?

• Hexokinase phosphorylates glucose

• phosphoglucomutase shifts the phosphate

• UDP-glucose pyrophosphorylase forms UDP-glucose

• glycogen synthase adds glucose to glycogen.

Where does glycogenesis occur inside the cell?

A. Mitochondrial matrix

B. Cytoplasm

C. Nucleus

D. Golgi apparatus

b.cytoplasm

2. Which enzyme forms α-1,4 glycosidic bonds during glycogenesis?

A. Glycogen phosphorylase

B. Glucose-6-phosphatase

C. Glycogen synthase

D. Debranching enzyme

C. Glycogen synthase

3. What is the activated form of glucose used for glycogen synthesis?

A. Glucose-6-phosphate

B. Glucose-1-phosphate

C. UDP-glucose

D. Free glucose

C. UDP-glucose

Which enzyme converts glucose-1-phosphate to glucose-6-phosphate in glycogenolysis?

A. Hexokinase

B. Phosphoglucomutase

C. Glycogen synthase

D. Glucose-6-phosphatase

B. Phosphoglucomutase

Why can liver glycogen help maintain blood glucose but muscle glycogen cannot directly do the same?

A. Muscle contains no glycogen

B. The liver lacks GLUT transporters

C. Muscle lacks glucose-6-phosphatase

D. The liver cannot perform glycolysis

C. Muscle lacks glucose-6-phosphatase

6. Which hormone promotes glycogen synthesis after a meal?

A. Glucagon

B. Epinephrine

C. Insulin

D. None of these

C. Insulin

7. What bond forms at a glycogen branch point?

A. α-1,4

B. α-1,6

C. β-1,4

D. Peptide bond

B. α-1,6

What does glycogen phosphorylase produce directly?

A. Free glucose

B. Glucose-6-phosphate

C. Glucose-1-phosphate

D. UDP-glucose

C. Glucose-1-phosphate

Which enzyme has a high affinity for glucose in muscle?

A. Glucokinase

B. Hexokinase

C. Glycogen phosphorylase

D. Glucose-6-phosphatase

B. Hexokinase

What are the two activities of the debranching enzyme?

A. Kinase and phosphatase

B. Transferase and α-1,6-glucosidase

C. Synthase and phosphorylase

D. Isomerase and ligase

B. Transferase and α-1,6-glucosidase

After glycogen phosphorylase acts, a glycogen branch is left with four glucose residues before the branch point. What happens next?

a) debranching enzymes acts, transferring three residues and removing the remaining residue

b) branching enzyme transfers 5-8 residues to form a new branch

c) phosphorylase continues through the branch point

d) glucose-6-phosphatase removes the branch point n the muscle

a) debranching enzymes acts, transferring three residues and removing the remaining residue

1. What does the glycogenesis pathway do

   1. It makes glucose

   2. It breaks down glycogen

   3. It breaks down glucose 

   4. It makes glycogen

1. It makes glycogen

1. What is the purpose of glycogen

   1. Gives energy to the liver when necessary

   2. Stored for blood glucose maintenance in muscle

   3. Gives energy for muscle contraction only

   4. Stores glucose for maintenance of blood glucose in liver

Stores glucose for maintenance of blood glucose in liver

1. How many grams of water are stored with each gram of glycogen

   1. 1-2/g

   2. 3-4/g

   3. 7g

   4. Water is not stored with glycogen

3-4/g

1. T/F the chain bonds of glycogen are in the alpha-1-4, glycosidic bonds

   1. True

   2. False

true

1. The fed state lasts for 

   1. 1-2 hour

   2. 6 hours

   3. 2-4 hours

   4. 0 hours

2-4 hrs

1. How many steps are there in glycogenesis

   1. 4

   2. 5

   3. 6

   4. 2

4

1. How many irreversible steps are there in glycogenesis

   1. 0

   2. 1

   3. 2

   4. 3

   5. 4

2

1. T/F glucokinase has a high affinity to glucose

   1. True

   2. False

false

1. What is the active form of glucose

   1. UTP-glucose

   2. UDP-glucose

   3. Glucose

   4. They’re all active

UDP-glucose

1. What is the enzyme in step 4 of glycogenesis’s name

   1. Glycogen synthase

   2. UDP-glucose-glycogenglucosyltransferase

   3. Glucose-1-phosphate uridyltransferase

   4. A and B

glycogen synthase

1. What steps are activated by insulin in glycogenesis

   1. 1

   2. 3

   3. 4

   4. A and C

A and C

1. T/F glucagon upregulates the glycogenesis pathway

   1. True

   2. False

false

1. The branching step happens every ____ glucose

   1. 4-6

   2. 3-4

   3. 5-8

   4. 11

5-8