Bio Lecture 25 Metabolic Signaling Flashcards Preview

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Flashcards in Bio Lecture 25 Metabolic Signaling Deck (20)
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1
Q

What are the two pathways that can be initiated by insulin binding to RTK?

A

RTK autophosphorylates and phosphorylates IRS-1.

IRS-1 recruits GRB-2 to signal the MAPK pathway. It also recruits PI3-K which activates the AKT pathway.

2
Q

What are the general effects of MAPK and AKT?

A

MAPK is involved in cell division and survival.

AKT affects muscle and adipose tissue by bringing Glut-4 to the surface to bring in glucose.

3
Q

How does insulin affect PKA?

A

It increases the activity of a phosphatase that dephosphorylates PKA substrates.
It decreases the activity of PKA by decreasing cAMP.

4
Q

How does glucagon affect PKA?

A

Glucagon binds to a G-coupled receptor which activates Adenylyl Cyclase and produces cAMP which activates PKA.

5
Q

What do insulin and glucagon do in terms of phosphorylation?

A

Insulin dephosphorylates

Glucagon phosphorylates

6
Q

What are the two enzymes in the liver that deal with glycogen production and break down?

A

Glycogen synthase makes it

Glycogen phosphorylase breaks it down

7
Q

What are the insulin counterregulatory hormones?

A

Glucagon, cortisol, epinephrine, norepinephrine.
Glucagon is released in response to blood glucose levels.
The others are released by neuronal signals in response to stress usually.

8
Q

When is epinephrine released?

A

Exercise, pain, hypoglycemia, hemorrhage, hypoxia

9
Q

What are the effects of epinephrine?

A

Tells pancreas to make more glucagon and less insulin.

Signals liver, muscle and adipose to mobilize macro molecules for oxidation.

10
Q

What are the effects of glucagon?

A

It only affects the liver. Promotes macromolecule breakdown and release of glucose into the blood. Gluconeogenesis from amino acids.

11
Q

Which hormones bind to G-coupled receptors?

A

Glucagon, epinephrine.

12
Q

What is beta oxidation?

A

converts fatty acids into acetyl coA and NADH, FADH2

13
Q

How does glucose get into the liver?

A

GLUT-2 transporter

14
Q

Summarize the actions of insulin, glucagon, epinephrine in the liver.

A

Insulin: glycogenesis, fatty acid synthesis

Glucagon/epinephrine: Gluconeogenesis, Glycogenolysis, ketogenesis

15
Q

Summarize hormone signaling in adipose tissue.

A

Insulin: uptake of glucose through GLUT-4, storage of TAGs made in the liver, lipogenesis

Epinephrine: Lipolysis to release fatty acids

16
Q

Summarize hormone signaling in muscle tissue.

A

Insulin: glucose uptake through GLUT-4 which can also happen through AMPK signaling from high levels of AMP. Does glycogenesis as well for muscle use only.

Epinephrine: glycogenolysis

17
Q

What happens to glucose brought into muscles through AMPK signaling?

A

It is catabolized and not stored. AMPK is activated my high levels of AMP meaning low energy in the cell.

18
Q

What activates AMPK?

A

High levels of AMP allosterically interact with AMPK and AMP also indirectly phosphorylates AMPK. Both enhance its activity significantly.

19
Q

What does metformin do?

A

It decreases ATP production in the mitochondria and thereby increases AMP levels in the cell. This activates AMPK. This brings GLUT-4 to the surface and glucose is taken up. It also decrease gluconeogenesis in the liver.

20
Q

What are the general effects of AMPK?

A

It shifts metabolic processes from ATP consuming to ATP producing. This means any kind of macromolecule synthesis is turned off and breakdown of molecules happens to produce energy.