Lecture 22 (Exam 2)

Question 1

This is a long chain homopolymer of glucose molecules with branches.

Answer 1

Glycogen

Question 2

In glycogen, the glucose molecules within the chain are linked together via…

Answer 2

alpha-1,4 glycosidic bonds

Question 3

In glycogen, the branch points formed __________ bonds between glucose monomers of separate chains.

Answer 3

alpha-1,6 glycosidic bonds

Question 4

_________ ends each contain a terminal glucose with a free hydroxyl group at carbon 4.

Answer 4

Non-reducing

Question 5

_________ end consists of glucose monomer connected to a protein called glycogenin.

Answer 5

Reducing

Question 6

Glycogen is stored where?

Answer 6

In the liver, muscle, and other tissues

Question 7

Glycogen is stored as ________ that contain not only glycogen but also the enzymes needed for glycogen metabolism. Defects in these enzymes can lead to disorders.

Answer 7

Granules

Question 8

_______ glycogen regulates blood glucose levels.

Answer 8

Liver

Question 9

_______ glycogen provides reservoir of fuel (glucose) for physical activity.

Answer 9

Muscle

Question 10

Glycogen metabolism is the regulated storage and release of ________.

Answer 10

Glucose

Question 11

Regulation of glycogen metabolism depends on ________ control, ________ modification through reversible phosphorylation of key enzymes, and ________ control.

Answer 11

Allosteric
Covalent
Hormonal

Question 12

What is the rate limiting enzyme of glycogenesis?

Answer 12

Glycogen synthase

Question 13

Glycogen synthase catalyzes the transfer of glucose from UDP-glucose to non-reducing end of glycogen chain. Forms ________ bonds between glucose molecules.

Answer 13

alpha-1,4 glycosidic bonds

Question 14

When the glycogen chain reaches _____ residues, a fragment of the chain (about 7 residues long) is broken off at an alpha-1,4 link and reattached elsewhere through an ________ link by ________ ________. The new branch point must be at least 4 residues away from a preexisting branch.

Answer 14

11
alpha-1,6 (glycosidic bond)
glucosyl (4:6) transferase

Question 15

Branching increases _________ of glycogen and increases number of terminal _________ ends.

Answer 15

Solubility

Non-reducing

Question 16

T/F. Branching of glycogen increases the rate at which glycogen can be synthesized and degraded.

Answer 16

True

Question 17

What is the rate-limiting enzyme of glycogenolysis?

Answer 17

Glycogen phosphorylase

Question 18

Glycogen is broken down to release…

Answer 18

Glucose 1-Phosphate 
Glycogen remnant (Glycogen n-1)

Question 19

In glycogenolysis, glucose 1-phosphate is converted to…

Answer 19

Glucose 6-phosphate

Question 20

Glucose 6-phosphate can be used for ________, free glucose for release into the _______ _______, or to the pentose phosphate pathway – NADPH and ribose derivative.

Answer 20

Glycolysis

Blood stream

Question 21

Glucose 6-phosphate cannot get out of the cell and only the liver has glucose 6-phosphatase. This converts it to _______ which can be released into the blood stream.

Answer 21

Glucose

Question 22

________ transfers a block of 3 of the remaining 4 glucose to the non-reducing end of the main chain forming an alpha-1,4 bond.

Answer 22

Transferase

Question 23

This is what cleaves the alpha-1,6 bond of the single remaining glucose residue to release the free glucose.

Answer 23

alpha-1,6 glucosidase

Question 24

Glycogen phosphorylase adds an _________ and releases a glucose residue as glucose 1-phosphate. It also uses _________ _________ as a cofactor.

Answer 24

Orthophosphate
Pyridoxal phosphate (Vitamin B6)