Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Foundations of Medicine > Week 3- Glycogen Metabolism > Flashcards

Week 3- Glycogen Metabolism Flashcards

1
Q

What tissue is dependent on glycolylis and ketone bodies to make acetyl CoA for TCA?

A

Brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is completely dependent on glycolyis for ATP?

A

RBCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is biggest?

Preproinsulin

Proinsulin

Insulin

A

Preproinsulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is proinsulin processed?

A

ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Insulin is stored in pancratic beta cell as a…

A

Hexamer wih Zn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is removed in converting proinsulin to insulin?

A

C-peptice

1:1 ration with insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The oxidation of odd chain length fatty acids produces succinyl CoA. When it moves into TCA, what are the products?

A

1 FAD, 1 NAD, GTP, Oxaloacetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What cells can secrete glucose?

A

Only hepatic cells…

Other bodily cells cannot…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is glycogen? What does it do in body?

A

Glycoge in a glucose storage molecule for most cell types but most important in:

Heart and skeletal muscle - serves as a buffer for glucose 6 phosphate for cellular use (energy)

In liver it serves as a glucose buffer for blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is glycogen?

A

Storage molecule for glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does glycogen do in liver and in heart and skeletal muscles

A

Serves as a buffer for glucose 6-phosphate for use within the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are symptoms of glycogen metabolism defects?

A

fasting hypoglycemia
muscle pain during exercise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Chemical structure of glucose?

What bonds make linear chains?

What bonds make branch points?

A

Two types of carbon – carbon bonds in glycogen:

1: 4 Bonds between the and 4 carbons make linear chains
1: 6 Bonds between the 1 and 6 carbons make branch points

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the substrates for glycogen synthesis?

A

Charged glucose.. must by phosphorylated…

G6P to G1P to UDP-Glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is UDP-glucose?

A

Glucose coiled on spring (energized)

Also has nucleotide handle for transport…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When the body make phospholipids, what is is simlar to? (process)

A

Similar to the process of creating UDP glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Structure of UDP-Glucose

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Basid structure of glycogen?

A

Glycogenen has serine OH groups on sides.. second sugar added through 1-4 linkage

It is a puff ball of branched glucoses…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the process for creating glycogen?

What is the enzyme for creating the long main chains?

A

Insulin signaling activates protein phosphatase-1, which dephosphorylates glycogen synthase, activating the enzyme.

In the absence of insulin, glycogen synthase kinase-3 is active, which phosphorylates and inactivates glycogen synthase.

This continues for 11 (or so) units of glucose

Elongation happens towards 4 carbon so always in 1 to 4 direction

Glycogen synthase adds UDP glucose to the linear chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the branching enzyme for glycogen production?

A

glycosyl 4-6 transferase

Branching enzyme (glycosyl 46 transferase) then cleaves a piece of the chain off, and attaches it to the chain in a 1:6 glycosidic linkage. Both branches then can be extended with 1:4 bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does glycosyl 4-6 transferase do?

A

Adds 6 UDP glucoses to a branched chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Draw branching of glycogen production rxn

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are key enzymes in glycogen synthesis (glycogenogensis)?

A

glycogen synthase

4-6 transferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do the key enzymes do in glycogenogensis?

A

Glycogen synthase adds a UDP glucose to a branched chain

then 4:6 glucose transferase transferes branched chains to main string of glucoses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is GSD 0

A

Defect in glycogen synthase… pts will ahve no glycogen production

Mutation in Glycogen Synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is GSD IV, Anderson disease?

A

Mutation in 4:6 transferase

The branched chains wnt get moved down to main linear chain..

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does GSD 0 cause?

A

Glycogen synthase deficiency

Rare (?) autosomal recessive

Normal glucose tolerance; variable clinical presentation of exercise intolerance, cardiac and muscle hypertrophy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is GSD IV?

A

Deficiency of branching enzyme, 4:6-transferase.

Failure to thrive, hepatomegaly, liver failure. Fatal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

So when have abundant carbs/glucose what happens?

A

Glycogen production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Glycogen is a what?

A

puffball of glucose…

It is a branched polymer

not linear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Why is it an advantage of glycogen to be branched? not linear?

A

Key: because it is branched.. multiple enzymes can chop it down much faster and at the same time so glucose can be made form glycogen VERY fast.. much faster than if it were a long chain. Multiple binding points for enzymes

It is a short term buffer for glucose concentration in blood…

Branching increases solubility (more exposed OH groups)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

If we dont have carb in blood? but have glycogen stores within cell what happens:

A

Glycogen degradation (glycogenolysis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What product from glycogenolysis?

A

G1P Glucose 1 phosphate

34
Q

What are three enzymes in glycogenolysis?

A

Glycogen phosphorylase

Makes the 1-4 cuts…

But, when it gets to a branchpoint it is sterrically hindered and cant act..

So 4:4 transferase moves it to end of chain

Then alpha 1,6 glucosidase removes the single G1P

Then glycogen phosphorylase breaks of the remaining glucose from chain..

35
Q

What enzyme can cut 1-4 bond and is not sterically hindered?

A

4-4 transferase

36
Q

What does alpha 1,6 glucosidase do?

A

Cuts one molecule of glucose from glycogen core

37
Q

Defect in glycogen degredation or one of key enzymes?

A

Can store glycogen but it wont be able to degredate it so you would see an increase in glycogen in tissues…

38
Q

What is 4:4 transferase?

A

Moves three glucoses to end of main glycogen chain when glycogen phosphorylase becomes sterically hindered..

39
Q

What is glygcogen phosphorylase?

A

Enzyme to cleaves glucose from glycogen chains and adds inorganic phosphate to make G1P

40
Q

What is alpha 1,6 glucosidase?

A

Enzyme that hydrolyzes the remaining glucose after 4:4 transferase removes the previous 3..

41
Q

Probs resulting form glycogen storage degredation disiease

A

Fasting hypoglycymia

Liver failure

42
Q

GSD V (Mcardles disease)

A

Caused by mutation in muscle glycogen phosphorylase

43
Q

GSD VI (Hers Disease)

A

Mutation in liver glycogen phosphorylase

44
Q

GSD III disease

A

Deficiency in 1,6 glucosidase activity

High levels of single glucoses on the glycogen core..

45
Q

How is glycogen metabolism regulated?

Which is faster? A or B?

A

There are two forms of glycogen phosphorylase: A and B

Shown is a Lineweaver-Burke plot (a.k.a. double reciprocal plot) of initial reaction velocities with different concentrations of substrate (glycogen) for phosphorylase A and phosphorylase B.

B form has higher 1/Vmax, therefore lower Vmax.
B form has higher (or less negative) 1/km, therefore Km is higher.

46
Q

FED vs FAST state and glycogen metabolism

A

Glycogen metabolism is controlled by phosphorylation of glycogen phosphorylase and glycogen synthase.

In the fed state, phosphorylase is inactive and glycogen synthase is active. Both are unphosphorylated.

In the fasted state, phosphorylase is active and glycogen synthase is inactive. Both are phosphorylated.

47
Q

Draw general lineweaver burk plot. Where is 1/vmax, 1/km

A

hj

48
Q

What is glycogen metabolism controlled by?

A

Phosphorylation of glycogen phosphorylase and glycogen synthase

49
Q

Glycogen metabolism in fasted state

A

Look at picture, draw it out..

50
Q

What inhibits and activates glycogen synthase?

A

Epinepherine and glucagon

51
Q

activates inhibits glycogen phosphorylase?

A

Glucagon and Ca++

52
Q

Protein phosphatase 1

A

activated by insulin (inactive in fasted)

53
Q

PLC (phosph lipase C)

A

Epinepherin ..

54
Q

DAG

PKC

IP3

A

diacyl glycerol

phosphoskinase C

inositol 3 phosphate

55
Q

Glycogen synthase is phosphorylated (deactivated) by what?

A

Epinepherine and glucagon

56
Q

What phosphorylizes glycogen phosphoylase kinase?

A

Glucagon (through PKA) adn Ca++

57
Q

What phosphorylates glycogen phophorylase?

A

Ca++ and PKA

58
Q

Draw glycogen metabolism in FED state in hepatocyte.

What inhibits protein phosphatase 1?

A

Insulin

59
Q

what inhibits glycogen synthase kinase 3?

A

PKB (Akt) through insulin

60
Q

Role of protein phosphatase?

A

When active, its role is to remove phosphates from glycogen synthase and glycogen phosphorylase

61
Q

Difference in kinases and phosphatases in regards to Pi and ATP..

A

….

62
Q

Cytoplasmic concentration of Ca?

A

Extremely Low

But waves of Ca come in from ER or Sarcoplatic Reticulum

63
Q

Know what epinephrine does… Ca calmudulin to kinase etc…

A

kj

64
Q

Whaere is Glucose 6 phosphatase found?

Take Phos off of G6P to put glucose in blood… ONLY IN LIVER. why is it critical?

A

(only in liver_not skel musc)

65
Q

What does wave of Ca do in muscle

A

Stimulates muscle contraction.. Then Ca goes to phosphorylate glycogen phosphorylase kinase.. This activateds glycogen phosphorylase KNow fasted vs fed state of this

66
Q

Glucose 6 phosphate in liver vs skeletal muscle…

A

lkj

67
Q

Draw glycogen metabolism in Fasted state in skeletal muscle

What does AMP to do AMP-K (kinase) and to glycogen phosphorylase?

A

lkj

68
Q

GSD 0

A

Glycogen synthase deficiency

Reduced glycogen storage efficiency

69
Q

GSD V

A

Deficiency of muscle glycogen phosphorylase.

Late childhood onset of exercise intolerance, myoglobinuria after exercise.

Increased creatine kinase; exagerated increase of creatine kinase and ammonia after exercise.

Treatment: Avoid exercise; try to build tolerance

70
Q

GSD I

A

Deficiency in glucose 6-phosphatase.

Fasting hypoglycemia, lactic acidosis. Hepatomegaly due to glycogen accumulation. Hyperuricemia and hyperlipidemia.

Treatment:
Avoid fasting by frequent feeding, uncooked cornstarch

71
Q

Blue cell and pink cell.. which is hepatocyte and which is muscle cell?

A

Hepatocyte on right

Can transport glucose out

Has glucose 6 phosphatease

AMP only in muscles

Ca from muscle contraction

Glucagon only acts on hepatocytes (not skeletal muscle)

GLucokinase in liver

Hexokinase in muscle

FASTED STATE

72
Q

Symptoms of GSD 0?

A

Glycogen synthase deficiency

Muscle Specific… Skeletal and Cardiac

If in Cardiac it is significant…

Normal glucose tolerance, variable clinical presentation of excercise intolerance…

Cardiac and skeletal muscle hypertrophy

May be cause of SIDS… unknown though

73
Q

GSD I Symptoms

A

Glucose 6 phosphatase

Only in liver*

Whole body glucohomeostacis problem…

Fasting hypoglycemia, lactic acidosis

Hepatomegaly due to glycogen accumulation

Hyperuricemia and hyperlipidemia

74
Q

GSD I Treatment?

A

Avoid fasting by frequent feeding, eating uncooked corn starch

75
Q

GSD III symptoms and treatment

A

Loss of debranching enzyme 1,6 glucosidase

Fasting hypoglycemia, ketoacidosis (starvation response)

Hyperlipidemia

Hepatomegaly with elevated ALT/AST

GSD III a - affects liver and muscle. can cause cardiac issues

GSD III b - affects only the liver

Treatment: frequent high carb meals

76
Q

GSD IV symptoms

A

Deficiency of branching enzymes, 4,6 transferase

Glycogen does not branch, justmany long chains

Failure to thrive, hepatomegaly, liver failure, can be fatal

77
Q

GSD V symptoms

A

Deficiency of muscle glycogen phosphorylase..

Late childhood onset of exercise intolerance, myoglobinuria after excercise

Increased creatine kinase

Exaggerated increase in ammonia after excercise

Treatment: avoid exercise, try to build tolerance

78
Q

What is general approach to child with fasting hypoglycemia…

A

adicocis vs no acidosis.. etc

79
Q

Clinical case I

8 year old south indian boy…

8 y/o male, died unexplained during excercise

mke card for consaguinous (first cousin parents)

Autopsy showed? Ragged red fibers. Tons of mitochondria and are swollen and nunnomral.. GLycogen depleted..

Sink fibrobalsts.. cultured in vitro in me dia containing. Plotted concentration of lactate vs time.

A

So muscles are trying to have aerobic production of energy but doesnt have glucose.. so it is producein energy form fatty acids and ketone bodies…

Mitochondria are porliferating to try to increase energy production

Plot.. lactate in control is from glucose stored as glycogten that goes throu anaerobic glycolosis. IN pt lactate is not being produces.. so not getting glucose from glycogen…

glycogen synthase (GYS1) western blot showd no blot for pateint but yes for control.. So pt not making GYS1 protein.. So the mutation prefents GYS1 from being produced. Then add GAPDH and it ensures same abount of protein in each sample..

80
Q

Summary of pathophysiology of excercise aindused suden cardiac arrest due to inherit4ed deficiency of muscle glycogen synthase

A

So deficiency in synthase. not able to store glucose as glycogen.. then in fasted state you have no glucose/energy. With no enrgy the muscle tissue compensated and produced many mitochondrial and hypertorphied. breaking up muscle fibers that eventually led to cardiac arrest…

so this boy was 8.. he compenstaed for many years, creating damage all the way along.

If a skin punch would have been done at birth… pt most likely could have been treated (by limited excercise). Is this plausable for every pt tho.. prob not.

81
Q

Next case.. Patient E..

PAS-pos.. Periotic acid shift stain - identifies sugars

So if take glycogen and incubate with amylase you get G6P..

So pictures show bad disfigureation of muscle

Phosphorylase kinase activity undetectable in heart

look at quiz slides online..

A
82
Q

What is different in liver and muscle glycogen phosphorylase?

A

liver - glucose

muscle - Glucose 6 phosphate

Foundations of Medicine (42 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions