Metabolic Cycle Regulation

Question 1

What are the three major energetic steps in glycolysis?

Answer 1

Glucose to G-6-P
Fructose-6-Phosphate to Fructose-1,6-Bisphosphate
PEP to Pyruvate

Question 2

What enzyme(s) catalyze Glucose to G-6-P?

Answer 2

Glucokinase (liver)

Hexokinase (extrahepatic cells)

Question 3

What enzyme(s) catalyze Fructose-6-Phosphate to Fructose-1,6-Bisphosphate?

Answer 3

Phosphofructokinase 1

Question 4

What enzyme(s) catalyze PEP to pyruvate?

Answer 4

Pyruvate Kinase

Question 5

What inhibits phosphofructokinase 1?

Answer 5

ATP and Citrate

Glucagon

Question 6

What activates phosphofructokinase 1?

Answer 6

ADP/AMP

F-2,6-Bisphosphate

Question 7

What inhibits Pyruvate kinase?

Answer 7

Long chain FA

Question 8

What activates pyruvate kinase?

Answer 8

ATP/Acetyl CoA

Question 9

What uses glucokinase/hexokinase and why?

Answer 9

Glucokinase: liver cells
Hexokinase: extra-hepatic cells
The liver uses glucokinase because it has a higher Km so the liver uses glucose at higher levels. This allows extra-hepatic cells to use hexokinase to breakdown glucose first before the liver cells when in a state of low glucose.

Question 10

How does insulin affect glycolysis?

Answer 10

Increases PFK-2 increasing glycolysis

Question 11

How does glucagon affect glycolysis?

Answer 11

Increases FBPase-2 decreasing glycolysis