glycogen synthesis

Question 1

what is the function of liver glycogen?

Answer 1

used to maintain glucose levels in the blood

stores glucose when glucose levels are too high and releases glucose when glucose levels are too low

Question 2

what is the function of muscle glycogen?

Answer 2

maintain muscle during bursts of activity

local energy store to allow muscles to do their first burst of energy

Question 3

what is the advantage of glycogen being less osmotically active than glucose?

Answer 3

can be stored

Question 4

why can liver glycogen be used to make glucose and not muscle glycogen?

Answer 4

liver has an enzyme which isn’t found in muscle tissue which allows glucose-6-phosphate to be dephosphorylated back to glucose

Question 5

in what ways can muscle glycogen be used to make ATP?

Answer 5

anaerobic glycolysis

aerobic metabolism

Question 6

what is glycogenic?

Answer 6

a protein primer

Question 7

which bonds join molecules of glucose together in glycogen?

Answer 7

carbon 1-4 links

Question 8

which end of glycogen is extended?

Answer 8

carbon 4 end

Question 9

which bond is needed to form a branch in glycogen?

Answer 9

carbon 1-6

Question 10

what enzyme is needed to form a glycogen branch?

Answer 10

glycogen branching enzyme

Question 11

after how many residues is a branch found in the main chain of glycogen?

Answer 11

every 12-14 residues

Question 12

what is the advantage of branches?

Answer 12

make glycogen and its energy easily accessible

helps solubility inside cell

Question 13

explain the process of glycogen synthesis

Answer 13

glucose-6-phosphate –> glucose-1-phosphate

UTP used to make UDP-glucose and PPi

Glycogen synthase removes UDP and adds glycogen onto the glycogen chain to extend it, with glycogenin as the primer

Question 14

how is glucose-6-phosphate converted into glucose-1-phosphate?

Answer 14

moving the phosphate from carbon 6 to carbon 1

Question 15

what is the energy from PPi –> 2Pi used for?

Answer 15

pushing UDP-glucose–> glycogen reaction to the right

Question 16

what effect does insulin have on glycogen synthase and glycogen?

Answer 16

insulin increases glucose storage into glycogen

glycogen synthase is active

Question 17

what effect does glucagon have on glycogen synthase and glycogen?

Answer 17

glucagon releases glucose into the blood

glycogen synthase is inactive

Question 18

how is glycogen synthase affected when it’s phosphorylated/dephosphorylated?

Answer 18

Phosphorylated – inactive

Dephosphorylated – active

Question 19

how does insulin dephosphorylate glycogen synthase?

Answer 19

activating protein phosphatase-1

Question 20

how is glycogen synthase phosphorylated?

Answer 20

protein kinase A and phosphorylase kinase

Question 21

what controls the phosphorylation of glycogen synthase?

Answer 21

cAMP
glucagon (liver)
adrenaline (muscle)

Question 22

what is glycogenolysis?

Answer 22

breakdown of glycogen

Question 23

what stimulates the breakdown of liver glycogen?

Answer 23

glucagon via phosphorylation of glycogen phosphorylase

Question 24

what enzyme breaks down glycogen?

Answer 24

glycogen phosphorylase

Question 25

what effect does phosphorylation and dephosphorylation have on glycogen phosphorylase?

Answer 25

Phosphorylated – active

Dephosphorylated – inactive

Question 26

what enzyme converts glucose-6-phosphate to glucose?

Answer 26

glucose-6-phosphatase

Question 27

what does muscle glycogen breakdown feed into?

Answer 27

glycolysis and energy production in that cell only

Question 28

under anaerobic conditions, what does glycolysis produce?

Answer 28

lactate

Question 29

describe the control of glycogen breakdown

Answer 29

Adrenaline + Glucagon activates adenylyl cyclase to convert ATP to cAMP
cAMP activates Protein Kinase A (PKA) to convert ATP to ADP.
phosphorylase kinase b into phosphorylase kinase a which then converts ATP to ADP
used to convert glycogen phosphorylase b to glycogen phosphorylase a
Glycogen phosphorylase cleaves glycogen to produce glucose-1-phosphate
then converted to glucose-6-phosphate

Question 30

what inheritance pattern are all glycogen storage diseases?

Answer 30

autosomal recessive

Question 31

what is the deficiency and consequence of type 1 - von Gierke’s?

Answer 31

glucose-6-phosphatase deficiency

leads to hypoglycaemia and lacticacidemina

Question 32

what is the deficiency and consequence of type 2 (Pompe’s)?

Answer 32

deficiency in lysosomal glycogen breakdown

leads to heart failure

Question 33

what is the deficiency and consequence of type 3 (Cori’s)?

Answer 33

deficiency in debranching enzyme

leads to hypoglycaemia

Question 34

what is the deficiency and consequence of type 4 (Andersen’s)?

Answer 34

deficiency in branching enzyme

unknown consequence

Question 35

what is the deficiency and consequence of type 5 (McArdle’s)?

Answer 35

deficiency in muscle phosphorylase

leads to exercise-induced cramps and fatigue

Question 36

what is the deficiency and consequence of type 6 (Her’s)

Answer 36

deficiency in liver phosphorylase

leads to hypoglycemia