glycogenesis and glycogenolysis

Question 1

what is glycogen

Answer 1

major storage form of glucose in mammalian cells

Question 2

what is glycogen formed by

Answer 2

linkage of individual glucose molecules

Question 3

describe the glycosidic bonds in glycogen

Answer 3

a 1,4 glycosidic bond forms the linear chain
a 1,6 glycosidic bond occurs at at least every 4th glucose residue to form branching points

Question 4

what form of glycogen is more soluable

Answer 4

branched is more soluble than a linear polymer

Question 5

what is the basics of the process glycogenesis

Answer 5

glucose is converted to glycogen immediately after eating a meal

Question 6

what is the average glycogen body storage in a 70kg man for 1 day of normal activity

Answer 6

about 450g (100g in the liver and 350g in muscles)

Question 7

what is the supply of glycogen used for

Answer 7

to power physical activity and to maintain vascular supply of glucose for oxidative metabolism to glucose-dependent tissues

Question 8

describe the movement of glucose through glycogenesis

Answer 8

1) glycogen synthase adds glucose to primer end of the pre-existing glycogen in an a-1,4 glycosidic bond
2) branching enzyme removes minimum of 7 glucose residues from elongating end
4)they are then attached via the a-1,6 glycosidic bond to internal position at least 4 glucose residues from a pre-existing branching point

Question 9

what are the basics of glycogenolysis

Answer 9

glycogen converted to G-1-P a few hours after a meal

Question 10

what happens during the first step of glycogenolysis

Answer 10

glycogen phosphorylase breaks a 1,4 glycosidic bonds using phosphoric acid

Question 11

what is the co-factor in glycogenolysis

Answer 11

pyridoxal-5-phosphate (vit B6)

Question 12

what does the debranching enzyme do during glycogenolysis

Answer 12

removes 3 glucose residues and transfers to a branch of another chain
4th/ last glucose molecule on the original branch released from a 1,6 glycosidic bond