glycogenolysis Flashcards

1
Q

what is the storage form of glucose?

A

glycogen

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2
Q

what are the primary storage sites for glycogen?

A

liver and skeletal muscle

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3
Q

what is a polymer?

A

many glucose molecules bound together

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4
Q

glycosidic chains of glucose are connected by?

A

a (1-4) bonds

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5
Q

glycosidic branch points of glucose are connected by?

A

a(1-6) bonds

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6
Q

glycogen branching occurs every?

A

10 glucose molecues

-provides increased solubility and easier access to glucose

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7
Q

where is glycogen found?

A

cytosol or cytoplasm

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8
Q

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

A

diet is insufficient
increased demand for ATP
gluconeogenesis is slow

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9
Q

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

A

glucose-6-phosphate

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10
Q

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

A

glycogen phosphorylase

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11
Q

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

A

pyridoxal phosphate

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12
Q

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

A

glucose-1-phosphate

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13
Q

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

A

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

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14
Q

what pathway uses glucose-6-phosphate?

A

glycolysis

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15
Q

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

A

lacks the enzyme needed to release glucose

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16
Q

glucose-6-phosphate is converted into?

A

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

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17
Q

what type of bond can glycogen phosphorylase not break?

A

a(1-6) bonds

18
Q

glycogen breakdown continues until?

A

we are 4 glucose residues away from the branch

19
Q

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

A

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

both a(1-6) enzymes

20
Q

what is the key regulatory enzyme of glycogenolysis?

A

glycogen phosphorylase

21
Q

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

A

glucagon
epinephrine
norepinephrine

22
Q

where is adenylyl cyclase located?

A

plasma membrane- catalyzes reaction resulting in cyclic AMP

23
Q

cAMP stimulates which powerful enzyme?

A

AMP kinase, PKA, protein kinase A

24
Q

glycogen phosphorylase B is active or inactive?

A

inactive

25
Q

AMP binds to glycogen phosphorylase A or B?

A

B

26
Q

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

A

inhibits it

27
Q

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

A

ATP binds to it and inhibits it

28
Q

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

A

glycogen phosphorylase kinase

29
Q

what releases calcium in the muscle?

A

neural stimulation

30
Q

what releases calcium in the liver?

A

epinephrine

31
Q

calmodulin is a subunit of what?

A

glycogen phosphorylase kinase

32
Q

neural stimulation releases calcium from where?

A

sarcoplasmic reticulum and binds to calmodulin

33
Q

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

A

adrenal medulla and it needs glucose

34
Q

the liver releases Ca from what and sends it where?

A

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

35
Q

where do you find glycogen in the brain?

A

astrocytes

embryonic neurons

36
Q

where is the highest concentration of glycogen in the brain?

A

where there is increased synaptic activity

2x more in gray matter than white matter

37
Q

what is essential for glutamate neurotransmission?

A

glycogen

38
Q

what stimulates glycogenolysis?

A
low energy- increased ADP AMP 
epinephrine/ norepinephrine
glucagon
calcium- muscle contraction, stress response 
AMP kinase
39
Q

what stimulates glycogenesis?

A

increased ATP

increased insulin or glucose

40
Q

what are the enzymes we need to know for glycogenolysis?

A
glycogen phosphorylase
phosphoglucomutase
glucosyl- (4:4)- transferase 
amylo-a-(1-6)- glucosidase 
glucose-6- phosphatase
41
Q

final reminder, where is glycogenolysis located?

A

cytosol