Random high yield things from Bessesen lectures

Question 1

In what way is gluconeogenesis different from glycolysis?

Answer 1

• It runs in reverse

- Goes from pyruvate –> oxaloacetate –> PEP instead of straight backwards

Question 2

Kids who can’t burn fat via TCA cycle present as what?

Answer 2

Hyperglycemia

Question 3

What tissue is most important source of glucose in blood?

Answer 3

Liver & Kidney because have G6P-ase (enzyme). Liver > Kidney

Question 4

What pathway level is responsible for a diabetic increased glucose level?

Answer 4

Gluconeogenesis

Question 5

What is the source of the carbons that make the glucose that is in a fasting diabetic’s blood?

Answer 5

Lactate from RBCs

Question 6

If a baby can’t sleep through the night, what is happening?

Answer 6

He is fasting and gets a neurologic problem. Depends upon his liver to produce glucose for his brain.

Question 7

Tissues and glycogen

Answer 7

Muscle - its own use

Liver - whole body

Question 8

Where does the glycogen pathway start and end?

Answer 8

Starts at glycogen

Ends at glucose-6-P (which goes on to glucose)

Question 9

Explain coordinate regulation of glycogen

Answer 9

You are either going to make glycogen or break it down, you won’t do both together

Question 10

UDP is a ___ form of glucose

Answer 10

high energy

Question 11

What is function of branched structure of glycogen

Answer 11

1. Rapid mobilization to glucose

2. Rapid storage as glycogen

Question 12

What serves as a protein anchor to start glycogen chain?

Answer 12

Glycogenin

Question 13

Which enzymes are critical for glycogen formation?

Answer 13

Glycogen synthase; only gives linear 1-4 structure. You need a branching enzyme (4:6 transferase) that counts 5 glucoses in to make a 1-6 bond for the branch.

Question 14

Contrast the functions of glycogen in the liver vs. muscle

Answer 14

1. Liver -> has glucose-6-phosphatase and can therefore turn it into glucose for the blood. 400g, doesn’t last you very long
2. Muscle - does not have the G6P enzyme, so it ends up using glycogen (via G6P input into glycolysis) for energy

Question 15

Key steps of glycogen (forward and backward pathway)

Answer 15

1. Forward to glycogen: Glycogen synthase from UDP-glucose –> Glycogen
   Branching enzyme as well.
2. Backward to G6P: Glycogenphosphorylase for Glycogen –> Glucose 1-P
   Debranching enzyme as well.

Question 16

In the liver, what things inhibit glycogen breakdown?

Answer 16

1. Glucose
2. ATP
3. G6P

Question 17

In the muscle, what things inhibit & stimulate glycogen breakdown?

Answer 17

1. G6P - inhibit
2. ATP - inhibit

These are indicators of exercise, which should stimulate breakdown

3. Ca++ - stimulate
4. AMP - stimulate

Question 18

Covalent modifiers of glycogen phosphorylase

Answer 18

1. Glucagon phosphorylates glycogen phosphorylase via phosphorylation of glycogen phosphorylase kinase –> glycogen breakdown
2. Insulin dephosphorylates glycogen phosphorylase kinase and glycogen phosphorylase (by glycogen phosphorylase kinase)

Question 19

When is glycogen phosphorylase kinase active? What is its role?

Answer 19

Active when it is phosphorylated

Role: put a phosphate group on glycogen phosphorylase to make it active

Question 20

Catabolic vs. Anabolic

Answer 20

Catabolic: associated with energy
Anabolic: associated with structure & function

Question 21

2 functions of HMP Shunt

Answer 21

1. Make NADPH (for synthesis of lipids)

2. 5-C skeleton (ribose sugars) for nucleotide synthesis

Question 22

Young patient comes in, treated for a UTI with a sulfa drug. They were jaundiced at birth and now have increased retic count, indirect bili, and free Hgb. What is the most likely cause of her problem? Why?

Answer 22

She is G6PD deficient
Gets a hemolytic anemia because it is necessary for the regeneration of NADP+ from glutathione reductase. Cannot relive the oxidant stress of drugs without G6PD.

Question 23

How can you distinguish between insulin you give someone and the insulin they make?

Answer 23

Measure C-peptide as this is the molecule of endogenous insulin production

Question 24

Actions of insulin

Answer 24

1. Increase glucose uptake into muscle
2. Increase glycogen synthesis
3. Mitogen
4. Na+ and H20 retention
5. Inhibits lipolysis
6. Inhibits ketogenesis
7. Changes blood flow

Question 25

GLP-1

Answer 25

1. Product of proglucagon gene from intestinal L-cells
2. Release is rapid in response to meals
3. Potent insulinotropic hormone (requires glucose to stimulate insulin secretion, this just potentiates it)
4. Impaired glucose tolerance and T2D manifest with lower plasma GLP-1 than controls

Question 26

3 hormones playing a role in T2D

Answer 26

1. Relative insulin deficiency
2. Relative glucagon excess
3. Relative GLP-1 deficiency