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MCB II Block 3 > Glycogen > Flashcards

Glycogen Flashcards

1
Q

glycogen is a polymer of

A

glucose

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2
Q

what is the main glycogen storage organ

A

liver

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3
Q

most glycogen disorders stem from what kind of abnormalities

A

liver

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4
Q

what allows the body energy in their storage for 24 hours

A

glucose and glycogen storage

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5
Q

what storage allows the body to survive for several weeks

A

triacylglycerol

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6
Q

will maternal glucose cross placenta to enter baby

A

yes

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7
Q

describe glycogen storage and a fetus/newborn

A

during the last few weeks, the baby will turn glucose into glycogen and store it in the liver.

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8
Q

describe what happens once baby is born regarding glucose/glycogen

A

when baby is born they are no longer receiving glucose through placenta, so glucose levels drop. this stimulates glycogenolysis

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9
Q

what happens to baby if mother is anorexic regarding glycogen

A

they will not have enough glycogen stored and will likely become hypoglycemic within their first few hours of birth

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10
Q

what is glycogen made out of

A

lots of glucose

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11
Q

what is the linkage of glucose in glycogen

A

α1,4 & α1, 6

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12
Q

describe the significance of the structure of glycogen

A

osmotic effects reduced

insoluble but reactive

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13
Q

how much glycogen is stored in liver

A

it varies with food intake. after eating more will be stored

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14
Q

glycogen in liver is used to buffer

A

blood plasma

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15
Q

if fasting when will glycogen in liver run out

A

12-24 hours

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16
Q

draw out glycogen in muscle pathway

A

pg 6

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17
Q

draw out glycogen in liver pathway

A

pg 6

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18
Q

is there glycogen in heart? explain

A

a little. there is a lot in purkinje conductors

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19
Q

is muscle glycogen affected by fasting

A

no

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20
Q

What does UDP G stand for

A

UDP glucose

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21
Q

UDP G is synthesized from

A

glucose 1 phosphate

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22
Q

UDP G is branch point for

A

glycogen synthesis

and other pathways

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23
Q

glycogen synthesis is catalyzed by what enzyme

A

by glycogen synthase and the branching enzyme.

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24
Q

glycogen degradation is catalyzed by what enzyme

A

glycogen phosphorylase and a debrancher enzyme

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25
Q

what is function of glucose 6 phosphatase

A

generates free glucose from G6P

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26
Q

what enzyme controls the interconverstion of glucose 6 phosphate and glucose 1 phosphate

A

phosphoglucomutase

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27
Q

what is the affect of galactose-1-phosphate uridyl transferase deficiency

A

hypoglycemia (glycogen metabolism is altered)

glycogen accumulation in liver

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28
Q

what is another name for glycogenin

A

Tyrosine-glycosyl transferase

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29
Q

how does the early fetus make glycogen when it has 0 glycogen

A

it forms the primer through glycogenin which autophosphorylates and self glucosylates

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30
Q

what kind of bond does glycogen synthase create

A

α1,4

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31
Q

where is glycgen synthase expressed

A

liver and muscle

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32
Q

where does glycogen synthase add add’l glycogen

A

adds additions at non reducing (OH) end

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33
Q

how is glycogen synthase shut off

A

phosphorylated

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34
Q

where is glycogen synthase phosphorylated

A

serine residue

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35
Q

each glycogen chain has how many residues

A

12-14

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36
Q

what enzyme allows branching to happen in glycogen

A

glycogen-branching enzyme (also called amylo (1→4) to (16) transglycosylase, or glycosyl-(4→6) transferase

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37
Q

draw out the glycogen synthase activation and inactivatino pathway

A

pg 12

top right

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38
Q

GSK3 requires priming by what

A

casein kinase

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39
Q

what activates PP1

A

insulin
glucose 6 phosphate
glucose

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40
Q

what inactivates PP1

A

glucagon

epinephrine

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41
Q

insulin signaling pathway increases what enzymes in muscle

A

hexokinase

glycogen synthase

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42
Q

what is functino of glycogen synthase

A

makes glycogen for energy storage

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43
Q

what is ultimately increasing the flux toward glycogen, esp in muscle

A

insulin affect on hexokinase

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44
Q

glucose transport in muscle is mediated by

A

GLUT4

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45
Q

exercise will increase what transporter

A

GLUT4

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46
Q

impaired glucose transport in skeletal muscle leads to what

A

contriutes to type 2 diabetes mellitus

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47
Q

cortisol induces

A

glycogen synthesis

48
Q

draw the glucose to glycogen pathway

A

pg 16

49
Q

describe the action of glycogen phosphorylase

A

removes single glucose residues by breaking α1, 4 linkages

50
Q

name two advantages of glycogen phosphorylase and how it works through phorphorylating step

A

.The glucose is removed from glycogen is an activated state, i.e. phosphorylated and this occurs without ATP hydrolysis.
2.The concentration of Piin the cell is high enough to drive the equilibrium of the reaction in the favorable direction since the free energy change of the standard state reaction is positive.

51
Q

what is pyridoxal phosphate

A

vitamin B6

52
Q

what does PLP stand for

A

Pyridoxal phosphate

53
Q

50% of body’s PLP is bound to

A

glycogen phosphorylase

54
Q

glycogen phosphorylase cannot remove glucose from

A

α1, 6 branches

55
Q

what is needed to remove the glucose connected by α1, 6 branches

A

glycogen debranching enzyme (GDE)

56
Q

what does GDE stand for

A

glycogen debranching enzyme

57
Q

what is the official name of GDE

A

amylo-1,6-glucosidase, 4-α-glucanotransferase

58
Q

describe the action of GDE

A

cleaves three glucose residues and transfers them to nonreducing endo f chain
cleaves the remainder α1,6 glucose and it becomes free glucose

59
Q

draw out the pathway of epinephrine and Ca2+ in glycogen degradation

A

pg 20

60
Q

epinephrine and Ca2+ oppose control of

A

synthase & phosphorylase

61
Q

what activates glycogen synthase

A

glucose 6 P

62
Q

what inactivates glycogen phosphorylase

A

Glucose 6P
ATP
Glucose

63
Q

Ca2+ in muscle promotes

A

glucose production & glycogen degradation

64
Q

what are the activators of breakdown of glycogen in muscle

A

Ca2+

AMP

65
Q

what are the inhibitors of glycogen breakdown in muscle

A

ATP

G6P

66
Q

what are the synthesis of glycogen activators in muscle

A

G6P

67
Q

what are the two states of glycogen phosphorylase

A

T or R

68
Q

what state can glycogen phosphorylase bind glycogen

A

R state

69
Q

R state of glycogen phosphorylase is enhanced byq

A

AMP

70
Q

R state of glycogen phosphorylase is inhibited by

A

ATP

G6P

71
Q

when fasting, what is main source of blood glucose in first 12-24 hours

A

glycogen degradation

72
Q

after 24 hours of fasting what is main source of blood glucose

A

gluconeogenesis

73
Q

if PFK1 is mutated what glycogen storage disease results

A

GSD VII - Tarui

74
Q

why does mutation of PFK1 cause a glycogen storage disease

A

If PFK1 is mutated, that means there is accumulation of G6P
G6P inhibits glycogen phosphorylase
glycogen phosphorylase is responsible for degradation of glycogen

75
Q

what is other name of GSD4

A

Anderson

76
Q

what kind of defiency is GSD4

A

branching enzyme deficiency in liver and muscle

77
Q

what is deficienct in GSD4

A

Transglucosidase

78
Q

how does GSD4 present

A

hepato-splenomegaly
muscle and liver structure damaged b/c branching of glycogen damaged
retardation
dead within 3 years common

79
Q

GSD5 stands for

A

McArdle

80
Q

where is deficiency in GSD5?

A

myoglycogen phosphorylase deficiency

81
Q

describe how pt with GSD5 presents

A

exercise intolerance

82
Q

what causes myoglycogen phosphorylase deficiency

A

genetic defect in phosphorylase (this affects breakdown of glycogen)

83
Q

GSD2 what is other name

A

Pompe

84
Q

GSD2 is due to

A

acidic α glucosidase deficiency

85
Q

describe what is happening in GSD2

A

lysosomal defect. body can’t get rid of glycogen, it accumulates. will have enlarged heart, floppy baby. usually die around 9 months

86
Q

what two mutations can cause von gierke disease

A

lack of glucose 6 phosphatase

translocase

87
Q

describe von gierke disease and why pt is not well

A

if there is no glucose 6 phosphatase, free glucose can’t be released from liver. → severe fasting hypoglycemia
increased G6P = increased PPP & increased glycolysis to pyruvate
more lactate production b/c more pyruvate
more Acetyl CoA b/c more pyruvate = more fatty acid synthesis
b/c there is more glycolysis → more glycerol 3 phosphate → triglyceride synthesis, hyperlipidemia
hepatomegaly, cirrohis

88
Q

GSD0 explain

A

it is not true GSD

glycogen synthase deficiency

89
Q

what are symptoms of GSD0

A 
hypoglycemia
lethargy
pallor
nausea
vomiting
sometimes seizures before breakfast
90
Q

what relieves hypoglycemia in pts with GSD0

A

protein rich meals

uncooked corn starch before bed

91
Q

what are the normal glucose levels for baby

A

3.3-10

92
Q

what are low glucose levels of baby after birth

A

1.5-less than 10

93
Q

why can’t glucagon signal myocyte?

A

myocyte doesn’t have receptors for glucagon

94
Q

draw epinephrine & glucagon pathway

A

pg 19, left pic

95
Q

draw epinephrine and glucagon covalent siganling control

A

pg 19 right pic

96
Q

what will nitric oxide to to BP

A

decrease

97
Q

what is the job of glycogen in cardiac muscle?

A

to produce oxaloacetate

98
Q

how does the cardiac cell producing oxaloacetate help it to make energy?

A

it increases capacity of TCA

99
Q

where is pyruate converted to oxaloacetate in cardiac muscle

A

mitochondria

100
Q

how does oxaloacetate help TCA cycle

A

Increases capacity of TCA cycle to process Acetyl CoA.

101
Q

what does glucose do to glycogen phosphorylase

A

exposes the phosphates so that insulin can come and take them off and inactivate

102
Q

what does insulin do to glycogen phosphorylase

A

removes the phosphates, inactivating it

103
Q

describe the symptoms of von gierke’s disease

A

pg 35

104
Q

in the liver, what happens to blood while fasting

A

glucagon increases

insulin decreases

105
Q

in liver, what happens to tissue while fasting

A

cAMP increases
glycogen degradation increases
glycogen synthesis decreases

106
Q

in liver, what happens to blood after carbohydrate meal

A

glucagon decreases

insulin increases

107
Q

in liver, what happens to tissue after carbohydrate meal

A

cAMP decreases
glucose increases
glycogen degradation decreases
glycogen synthesis increases

108
Q

in liver what happens to blood during exercise and stress

A

epinephrine increases

109
Q

in liver, what happens to tissue during exercise and stress

A

IP3 increases
Ca2+ calmodulin increases
glycogen degradation increases
glycogen synthesis decreases

110
Q

in muscle, what happens to blood while fasting (rest)

A

insulin decreases

111
Q

in muscle, what happens to tissue while fasting (rest)

A

glycogen synthesis decreases

glucose transport decreases

112
Q

in muscle, what happens to blood after carbohydrate meal while at rest

A

insulin increases

113
Q

in muscle, what happens to tissue after carbohydrate meal while at rest

A

glycogen synthesis increases

glucose transport increases

114
Q

in muscle what happens to blood during exercise

A

epinephrine increases

115
Q

in muscle, what happens to tissue during exercise

A 
AMP increases
Ca2+ calmodulin increases
cAMP increases
glycogen degradation increases
glycolysis increases

MCB II Block 3 (6 decks)

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