Glucose

Question 1

How is glycogen stored in muscle and liver cells of vertebrates

Answer 1

cystosolic granulaes

Question 2

what is glycogenolysis

Answer 2

the degradation of glycogen

Question 3

what does glycogen breakdown yield?

Answer 3

G1P which can be converted to G6P for metabolism via glycolysis and the citric acid cycle

Question 4

What is most of the G6P in the liver converted to?

Answer 4

it is converted to glucose and delivered to other cells such as the brain, enthrocytes and adipocytes

Question 5

What does glycogen phosphorlase catalyze?

Answer 5

phosphorylysis which cleaves the bond by transferring an oxygen atom of phosphate

Question 6

Where does the enzyme remove the residues from?

Answer 6

the non-reducing ends of the glycogen

Question 7

What specific glucose molecules does glycogen phosphorylase act on? Where does it stop?

Answer 7

it acts on 1-4 linkages

4 residues from the branching point

Question 8

What is GP?

Answer 8

It is a dimer of 2 identical lobed subunits

Question 9

Where are catalytic sites?

Answer 9

they are in the clefts between the two domains of each subunit.

Question 10

What is the difference between phosphorylase a and phosphorylase b?

Answer 10

a- is the more active form

b- the less active form. It is dephosphorylated

Question 11

After glycogen phosphorylase is finished what is the product and what happens to it?

Answer 11

the result is limit dextrin, which is further degraded by the glycogen-debranching enzyme.

Question 12

How many glucose residues does glucanotransferase relocate? The debranching enzyme catalyzes the removal of what linked glucose?

Answer 12

3

the alpha 1-6 linked

Question 13

How many ATPs are yielded by each glucose molecule

Answer 13

3 ATP

Question 14

How is G1P conversted to G6P?

Answer 14

phosphoglucomutase

Question 15

What is the significance of G6P?

Answer 15

it is an intermediate of several cellular pathways

Question 16

How much dietary glucose is converted to glycogen?

Answer 16

2/3

Question 17

How is cellular glucose converted to G6P?

Answer 17

Hexokinase

Question 18

What is a major regulatory step in glycogen synthesis?

Answer 18

Glycogen synthase

Question 19

What is the enzyme intermediate in the first step between G6P and G1P?`

Answer 19

phosphoglucomutase

Question 20

the second step in glycogen synthesis is G6P to UDP glucose. What is the enzyme intermediate?

Answer 20

UDP-glucose pyrophosphorlase

Question 21

What is the last enzyme used in the glycogen synthesis process when going from UDP-glucose to Glycogen?

Answer 21

glycogen synthase

Question 22

Which side of glycogen does glycogen synthase add glucose onto?

Answer 22

the non-reducing end

Question 23

What are the three hormones that regulate glycogen metabolism?

Answer 23

Insulin, glucagon and adrenaline

Question 24

What is muscle glycogen used for?

Answer 24

it is fuel for muscle contraction

Question 25

What is liver glycogen used for?

Answer 25

converted to glucose for the bloodstream transport to other tissues

Question 26

Where is insulin produced and when is it secreted?

Answer 26

it is created in the beta cells of the pancreas, and is secreted when the glucose levels of the blood are high because of the fed state)

Question 27

What does insulin do?

Answer 27

it increases the availability of the GLUT4 transporters on the cell surface for the cell to take up more glucose into muscle and adipose tissue.

Question 28

How does insulin stimulate glycogen synthesis in the liver?

Answer 28

-causes a depolarization of a specific site on glycogen synthase and affects the signaling pathway and the protein kinase cascade.

Question 29

Where is glucagon created and when is it secreted?

Answer 29

It is created in the beta cells of the pancreas. and is secrete when the blood indicates low levels of glucose present.

Question 30

What does glucagon stimulate?

Answer 30

It stimulates glycogen degradation to restore blood glucose to steady-state levels.

Question 31

What cells are the only ones rich in glucagon receptors

Answer 31

liver cells

Question 32

Where is adrenaline released from

Answer 32

released from the adrenal glands in response to the flight or fight mechanism

Question 33

What does adrenaline stimulate?

Answer 33

the breakdown of glycogen to G1P- which is later converted to G6P. the increases amount of g6P increases both the rate of glycolysis in the muscle and the glucose release into the blood stream.

Question 34

What two enzymes control glycogen metabolism in liver and muscle cells?

Answer 34

glycogen phosphorylase and glycogen synthase

Question 35

True or false: when glycogen phosphorylase is active, glycogen synthase is also active.

Answer 35

false, when GP is active, GS will be inactive. They are reciprocally regulated.

Question 36

How does covalent regulation occur?

Answer 36

by phosphorylation (added a phosphate) and dephosphorylation (adding a OH group)

Question 37

Is the phosphorylated form of (active form) of GP inhibited by G6P?

Answer 37

yes

Question 38

Is the active form (dephosphorylated form) of GS inhibited G6P?

Answer 38

no, it is activated