Glycogen Flashcards
(115 cards)
1
Q
glycogen is a polymer of
A
glucose
2
Q
what is the main glycogen storage organ
A
liver
3
Q
most glycogen disorders stem from what kind of abnormalities
A
liver
4
Q
what allows the body energy in their storage for 24 hours
A
glucose and glycogen storage
5
Q
what storage allows the body to survive for several weeks
A
triacylglycerol
6
Q
will maternal glucose cross placenta to enter baby
A
yes
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.
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
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
10
Q
what is glycogen made out of
A
lots of glucose
11
Q
what is the linkage of glucose in glycogen
A
α1,4 & α1, 6
12
Q
describe the significance of the structure of glycogen
A
osmotic effects reduced
insoluble but reactive
13
Q
how much glycogen is stored in liver
A
it varies with food intake. after eating more will be stored
14
Q
glycogen in liver is used to buffer
A
blood plasma
15
Q
if fasting when will glycogen in liver run out
A
12-24 hours
16
Q
draw out glycogen in muscle pathway
A
pg 6
17
Q
draw out glycogen in liver pathway
A
pg 6
18
Q
is there glycogen in heart? explain
A
a little. there is a lot in purkinje conductors
19
Q
is muscle glycogen affected by fasting
A
no
20
Q
What does UDP G stand for
A
UDP glucose
21
Q
UDP G is synthesized from
A
glucose 1 phosphate
22
Q
UDP G is branch point for
A
glycogen synthesis
and other pathways
23
Q
glycogen synthesis is catalyzed by what enzyme
A
by glycogen synthase and the branching enzyme.
24
Q
glycogen degradation is catalyzed by what enzyme
A
glycogen phosphorylase and a debrancher enzyme
25
what is function of glucose 6 phosphatase
generates free glucose from G6P
26
what enzyme controls the interconverstion of glucose 6 phosphate and glucose 1 phosphate
phosphoglucomutase
27
what is the affect of galactose-1-phosphate uridyl transferase deficiency
hypoglycemia (glycogen metabolism is altered)
| glycogen accumulation in liver
28
what is another name for glycogenin
Tyrosine-glycosyl transferase
29
how does the early fetus make glycogen when it has 0 glycogen
it forms the primer through glycogenin which autophosphorylates and self glucosylates
30
what kind of bond does glycogen synthase create
α1,4
31
where is glycgen synthase expressed
liver and muscle
32
where does glycogen synthase add add'l glycogen
adds additions at non reducing (OH) end
33
how is glycogen synthase shut off
phosphorylated
34
where is glycogen synthase phosphorylated
serine residue
35
each glycogen chain has how many residues
12-14
36
what enzyme allows branching to happen in glycogen
glycogen-branching enzyme (also called amylo (1→4) to (16) transglycosylase, or glycosyl-(4→6) transferase
37
draw out the glycogen synthase activation and inactivatino pathway
pg 12
| top right
38
GSK3 requires priming by what
casein kinase
39
what activates PP1
insulin
glucose 6 phosphate
glucose
40
what inactivates PP1
glucagon
| epinephrine
41
insulin signaling pathway increases what enzymes in muscle
hexokinase
| glycogen synthase
42
what is functino of glycogen synthase
makes glycogen for energy storage
43
what is ultimately increasing the flux toward glycogen, esp in muscle
insulin affect on hexokinase
44
glucose transport in muscle is mediated by
GLUT4
45
exercise will increase what transporter
GLUT4
46
impaired glucose transport in skeletal muscle leads to what
contriutes to type 2 diabetes mellitus
47
cortisol induces
glycogen synthesis
48
draw the glucose to glycogen pathway
pg 16
49
describe the action of glycogen phosphorylase
removes single glucose residues by breaking α1, 4 linkages
50
name two advantages of glycogen phosphorylase and how it works through phorphorylating step
. The glucose is removed from glycogen is an activated state, i.e. phosphorylated and this occurs without ATP hydrolysis.
2. The concentration of Pi in 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
what is pyridoxal phosphate
vitamin B6
52
what does PLP stand for
Pyridoxal phosphate
53
50% of body's PLP is bound to
glycogen phosphorylase
54
glycogen phosphorylase cannot remove glucose from
α1, 6 branches
55
what is needed to remove the glucose connected by α1, 6 branches
glycogen debranching enzyme (GDE)
56
what does GDE stand for
glycogen debranching enzyme
57
what is the official name of GDE
amylo-1,6-glucosidase, 4-α-glucanotransferase
58
describe the action of GDE
cleaves three glucose residues and transfers them to nonreducing endo f chain
cleaves the remainder α1,6 glucose and it becomes free glucose
59
draw out the pathway of epinephrine and Ca2+ in glycogen degradation
pg 20
60
epinephrine and Ca2+ oppose control of
synthase & phosphorylase
61
what activates glycogen synthase
glucose 6 P
62
what inactivates glycogen phosphorylase
Glucose 6P
ATP
Glucose
63
Ca2+ in muscle promotes
glucose production & glycogen degradation
64
what are the activators of breakdown of glycogen in muscle
Ca2+
| AMP
65
what are the inhibitors of glycogen breakdown in muscle
ATP
| G6P
66
what are the synthesis of glycogen activators in muscle
G6P
67
what are the two states of glycogen phosphorylase
T or R
68
what state can glycogen phosphorylase bind glycogen
R state
69
R state of glycogen phosphorylase is enhanced byq
AMP
70
R state of glycogen phosphorylase is inhibited by
ATP
| G6P
71
when fasting, what is main source of blood glucose in first 12-24 hours
glycogen degradation
72
after 24 hours of fasting what is main source of blood glucose
gluconeogenesis
73
if PFK1 is mutated what glycogen storage disease results
GSD VII - Tarui
74
why does mutation of PFK1 cause a glycogen storage disease
If PFK1 is mutated, that means there is accumulation of G6P
G6P inhibits glycogen phosphorylase
glycogen phosphorylase is responsible for degradation of glycogen
75
what is other name of GSD4
Anderson
76
what kind of defiency is GSD4
branching enzyme deficiency in liver and muscle
77
what is deficienct in GSD4
Transglucosidase
78
how does GSD4 present
hepato-splenomegaly
muscle and liver structure damaged b/c branching of glycogen damaged
retardation
dead within 3 years common
79
GSD5 stands for
McArdle
80
where is deficiency in GSD5?
myoglycogen phosphorylase deficiency
81
describe how pt with GSD5 presents
exercise intolerance
82
what causes myoglycogen phosphorylase deficiency
genetic defect in phosphorylase (this affects breakdown of glycogen)
83
GSD2 what is other name
Pompe
84
GSD2 is due to
acidic α glucosidase deficiency
85
describe what is happening in GSD2
lysosomal defect. body can't get rid of glycogen, it accumulates. will have enlarged heart, floppy baby. usually die around 9 months
86
what two mutations can cause von gierke disease
lack of glucose 6 phosphatase
| translocase
87
describe von gierke disease and why pt is not well
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
GSD0 explain
it is not true GSD
| glycogen synthase deficiency
89
what are symptoms of GSD0
```
hypoglycemia
lethargy
pallor
nausea
vomiting
sometimes seizures before breakfast
```
90
what relieves hypoglycemia in pts with GSD0
protein rich meals
| uncooked corn starch before bed
91
what are the normal glucose levels for baby
3.3-10
92
what are low glucose levels of baby after birth
1.5-less than 10
93
why can't glucagon signal myocyte?
myocyte doesn't have receptors for glucagon
94
draw epinephrine & glucagon pathway
pg 19, left pic
95
draw epinephrine and glucagon covalent siganling control
pg 19 right pic
96
what will nitric oxide to to BP
decrease
97
what is the job of glycogen in cardiac muscle?
to produce oxaloacetate
98
how does the cardiac cell producing oxaloacetate help it to make energy?
it increases capacity of TCA
99
where is pyruate converted to oxaloacetate in cardiac muscle
mitochondria
100
how does oxaloacetate help TCA cycle
Increases capacity of TCA cycle to process Acetyl CoA.
101
what does glucose do to glycogen phosphorylase
exposes the phosphates so that insulin can come and take them off and inactivate
102
what does insulin do to glycogen phosphorylase
removes the phosphates, inactivating it
103
describe the symptoms of von gierke's disease
pg 35
104
in the liver, what happens to blood while fasting
glucagon increases
| insulin decreases
105
in liver, what happens to tissue while fasting
cAMP increases
glycogen degradation increases
glycogen synthesis decreases
106
in liver, what happens to blood after carbohydrate meal
glucagon decreases
| insulin increases
107
in liver, what happens to tissue after carbohydrate meal
cAMP decreases
glucose increases
glycogen degradation decreases
glycogen synthesis increases
108
in liver what happens to blood during exercise and stress
epinephrine increases
109
in liver, what happens to tissue during exercise and stress
IP3 increases
Ca2+ calmodulin increases
glycogen degradation increases
glycogen synthesis decreases
110
in muscle, what happens to blood while fasting (rest)
insulin decreases
111
in muscle, what happens to tissue while fasting (rest)
glycogen synthesis decreases
| glucose transport decreases
112
in muscle, what happens to blood after carbohydrate meal while at rest
insulin increases
113
in muscle, what happens to tissue after carbohydrate meal while at rest
glycogen synthesis increases
| glucose transport increases
114
in muscle what happens to blood during exercise
epinephrine increases
115
in muscle, what happens to tissue during exercise
```
AMP increases
Ca2+ calmodulin increases
cAMP increases
glycogen degradation increases
glycolysis increases
```
