glycogenolysis

Question 1

what is the storage form of glucose?

Answer 1

glycogen

Question 2

what are the primary storage sites for glycogen?

Answer 2

liver and skeletal muscle

Question 3

what is a polymer?

Answer 3

many glucose molecules bound together

Question 4

glycosidic chains of glucose are connected by?

Answer 4

a (1-4) bonds

Question 5

glycosidic branch points of glucose are connected by?

Answer 5

a(1-6) bonds

Question 6

glycogen branching occurs every?

Answer 6

10 glucose molecues

-provides increased solubility and easier access to glucose

Question 7

where is glycogen found?

Answer 7

cytosol or cytoplasm

Question 8

what are some reasons why we would need to begin glycogen degradation or breakdown?

Answer 8

diet is insufficient
increased demand for ATP
gluconeogenesis is slow

Question 9

when exercising, glycogen in muscle can break down and release what?

Answer 9

glucose-6-phosphate

Question 10

what enzyme do we need to break a(1-4) bonds?

Answer 10

glycogen phosphorylase

Question 11

what coenzyme does glycogen phosphorylase need to break the a(1-4) bond?

Answer 11

pyridoxal phosphate

Question 12

what is the product when we break the a(1-4) bond?

Answer 12

glucose-1-phosphate

Question 13

what is glucose-1-phosphate converted into glucose-6-phosphate by?

Answer 13

phosphoglucomutase- I think we just need to know its a mutase

Question 14

what pathway uses glucose-6-phosphate?

Answer 14

glycolysis

Question 15

once glucose is trapped in a muscle it is not available for other tissues, why?

Answer 15

lacks the enzyme needed to release glucose

Question 16

glucose-6-phosphate is converted into?

Answer 16

free glucose where it is sent to the cytosol and released into the blood stream

Question 17

what type of bond can glycogen phosphorylase not break?

Answer 17

a(1-6) bonds

Question 18

glycogen breakdown continues until?

Answer 18

we are 4 glucose residues away from the branch

Question 19

what are the 2 enzymes required to cut the glucose branches?

Answer 19

glucosyl (4:4) transferase
amylo-a (1-6) glucosidase

both a(1-6) enzymes

Question 20

what is the key regulatory enzyme of glycogenolysis?

Answer 20

glycogen phosphorylase

Question 21

what hormones attach to the cell membrane and activate adenylyl cyclase to produce cAMP?

Answer 21

glucagon
epinephrine
norepinephrine

Question 22

where is adenylyl cyclase located?

Answer 22

plasma membrane- catalyzes reaction resulting in cyclic AMP

Question 23

cAMP stimulates which powerful enzyme?

Answer 23

AMP kinase, PKA, protein kinase A

Question 24

glycogen phosphorylase B is active or inactive?

Answer 24

inactive

Question 25

AMP binds to glycogen phosphorylase A or B?

Answer 25

B

Question 26

AMP binding to glycogen phosphorylase B does what to glycogen synthesis?

Answer 26

inhibits it

Question 27

what binds to glycogen phosphorylase A and what does it do to it?

Answer 27

ATP binds to it and inhibits it

Question 28

when calcium binds to calmodulin to form the CaCaM complex what gets activated?

Answer 28

glycogen phosphorylase kinase

Question 29

what releases calcium in the muscle?

Answer 29

neural stimulation

Question 30

what releases calcium in the liver?

Answer 30

epinephrine

Question 31

calmodulin is a subunit of what?

Answer 31

glycogen phosphorylase kinase

Question 32

neural stimulation releases calcium from where?

Answer 32

sarcoplasmic reticulum and binds to calmodulin

Question 33

where is epinephrine released from and what does it need to release?

Answer 33

adrenal medulla and it needs glucose

Question 34

the liver releases Ca from what and sends it where?

Answer 34

it releases it from the ER and sends it to the cytoplasm

Question 35

where do you find glycogen in the brain?

Answer 35

astrocytes | embryonic neurons

Question 36

where is the highest concentration of glycogen in the brain?

Answer 36

where there is increased synaptic activity 2x more in gray matter than white matter

Question 37

what is essential for glutamate neurotransmission?

Answer 37

glycogen

Question 38

what stimulates glycogenolysis?

Answer 38

``` low energy- increased ADP AMP epinephrine/ norepinephrine glucagon calcium- muscle contraction, stress response AMP kinase ```

Question 39

what stimulates glycogenesis?

Answer 39

increased ATP | increased insulin or glucose

Question 40

what are the enzymes we need to know for glycogenolysis?

Answer 40

``` glycogen phosphorylase phosphoglucomutase glucosyl- (4:4)- transferase amylo-a-(1-6)- glucosidase glucose-6- phosphatase ```

Question 41

final reminder, where is glycogenolysis located?

Answer 41

cytosol