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Biochemistry > L29 Diabetes & Control of Glycogen Metabolism > Flashcards

L29 Diabetes & Control of Glycogen Metabolism Flashcards

1
Q

Glycogen metabolism must be…

A

Tightly regulated!

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2
Q

Allosteric control of glycogen metabolism is…

A

Slow

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3
Q

There are 3 fast ways to regulate glycogen metabolism…

A
  1. Epinephrine
  2. Glucagon
  3. Insulin
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4
Q

Epinephrine acts on which receptors in the muscle and liver?

A

G-protein coupled receptors

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5
Q

Epinephrine binds to G-protein coupled receptors to initiate a…

A

cAMP dependent phosphorylation cascade resulting in mass breakdown of glycogen

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6
Q

Epinephrine triggers the mass breakdown of glycogen, for what sort of situation?

A

Emergencies

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7
Q

Insulin and glucagon are secreted from the…

A

Islet cells of the pancreas

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8
Q

Insulin is produced in the ( β / ⍺ ) islet cells…

A

β

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9
Q

Glucagon is produced in the ( β / ⍺ ) islet cells…

A

⍺

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10
Q

The islet cells of the pancreas are highly…

A

Vascularised

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11
Q

Which is more important to blood sugar regulation…

a) The absolute levels of insulin and glucagon
b) The ratio of insulin to glucagon
c) Only the absolute levels of insulin

A

b) The ratio of insulin to glucagon

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12
Q

Glucagon binds to receptors in the…

a) Liver and muscle cells
b) Muscle cells
c) Liver cells

A

c) Liver cells

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13
Q

On binding to the receptor, glucagon has the effect of (4)…

A
  • Increasing glucose release
  • Increasing glycogen breakdown
  • Increasing gluconeogenesis
  • Decreasing glycogen synthesis
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14
Q

Insulin binds to receptors in the…

a) Liver and muscle cells
b) Muscle cells
c) Liver cells

A

a) Liver and muscle cells

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15
Q

Insulin has the effect of (4)…

A
  • Increasing glucose uptake
  • Decreasing glycogen breakdown
  • Decreasing gluconeogenesis
  • Increasing glycogen synthesis
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16
Q

Both glycogen and insulin can be controlled by…

A

Phosphorylation

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17
Q

Phosphorylation has what effect on glycogen phosphorylase?

A

Activation (which leads to glycogen breakdown)

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18
Q

Phosphorylation has what effect on glycogen synthase?

A

Deactivation (which stops glycogenesis)

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19
Q

Insulin and glucagon:

a) act via G-protein linked receptors
b) act via different receptor types
c) act via enzyme-linked receptors

A

b) act via different receptor types

20
Q

Epinephrine and glucagon:

a) act via G-protein linked receptors
b) act via different receptor types
c) act via enzyme-linked receptors

A

a) act via G-protein linked receptors

21
Q

Insulin:

a) acts via G-protein linked receptors
b) acts via different receptor types
c) acts via enzyme-linked receptors

A

c) acts via enzyme-linked receptors

22
Q

Both epinephrine and glucagon bind to G-Protein linked receptors, initiating a cAMP dependent phosphorylation cascade resulting in the…

A
  • Activation of glycogen phosphorylase
  • Deactivation of glycogen synthase

(they both get phosphorylated as part of the cascade, but as mentioned on another question, it has opposite effects on each)

23
Q

Insulin binds to an enzyme linked receptors known as…

A

Receptor tyrosine kinase

24
Q

Receptor tyrosine kinase phosphorylates…

A

IRS

25
Q

The end result of insulin binding to the receptor tyrosine kinase is the dephosphorylation of…

A

Glycogen synthase, which leads to more glycogenesis (pulling glucose from the blood in order to do so)

26
Q

Glucose transporters are known as…

A

GLUT

27
Q

There are…

a) 16 types of GLUT with varying affinity for glucose
b) 16 types of GLUT with equal affinity for glucose
c) 27 types of GLUT with equal affinity for glucose
d) 3 types of GLUT with varying affinity for glucose

A

a) 16 types of GLUT with varying affinity for glucose

28
Q

GLUT 1 & 3 are found in…

A

All mammalian tissues

29
Q

GLUT2 is found in…

A

Liver and pancreatic β-cells

30
Q

Compared with GLUT1 & 3, GLUT2 has a…

A

Much higher Km (lower affinity)

31
Q

GLUT4 is found in…

A

Muscle and fat cells

32
Q

The glucose affinity of GLUT4 is…

a) More than GLUT 1, 2, 3
b) Less than GLUT 1 & 2, but more than GLUT 3
c) Between GLUT 1 & 3 and GLUT 2
d) Less than GLUT 1 & 3

A

c) Between GLUT 1 & 3 and GLUT2

33
Q

Insulin stimulates the movement of ? to the plasma membrane

A

GLUT4

34
Q

By stimulating movement of GLUT4 to the plasma membranes, insulin increases…

A

Glucose uptake

35
Q

Type 1 diabetes represents approximately what proportion of diabetes cases?

A

10%

36
Q

Type 1 diabetes is also known as…

A

Insulin-dependent diabetes

as there is an absolute insulin deficiency

37
Q

Type 1 diabetes is currently treated via…

A

Exogenous insulin injections or pancreas/islet transplants

38
Q

In the future Type 1 diabetes could potentially be treated by (3)…

A
  • Xenotransplantation
  • iPS or EPS stem cells to generate new beta cells
  • Immunomodulation
39
Q

Type 2 diabetes represents approximately what proportion of diabetes cases?

A

90%

40
Q

In type 2 diabetes, hyperinsulinemia leads to…

A

Insulin resistance

41
Q

It was previously thought that insulin resistance was followed by insulin deficiency caused by…

A

Beta cell death

42
Q

New evidence suggests that in type 2 diabetes beta cells…

A

Don’t die, but hide away to avoid death

43
Q

Type 2 diabetes is reversible, for example with…

A

A low calorie (e.g. 800 calorie) diet

44
Q

Diabetes is caused by problems with…

A

Insulin signalling

45
Q

In hyperglycaemia, the kidneys can’t cope, leading to (3)…

A
  • Renal loss of glucose*
  • Large volumes of urine
  • Dehydration and excessive thirst

*hence the full name diabetes mellitus, mellitus meaning sweet, as glucose in urine gives a sweet smell 👃

Biochemistry (21 decks)

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