9.4-9.5 Glycolysis Regulation

Question 1

Which steps of glycolysis are irreversible?

Answer 1

Steps 1,3,10

Question 2

Which enzymes are involved with the irreversible steps?

Answer 2

Hexokinase, phosphofructokinase-1, pyruvate kinase

Question 3

How is step one regulated?

Answer 3

Feedback inhibition by product

Question 4

Hexokinase

Answer 4

Most cell types use, binds hexoses, smaller Km so greater BA, Inhibited by G6P

Question 5

Glucokinase

Answer 5

Liver and pancreas, specific to glucose, larger Km = lower BA, not inhibited by G6P

Question 6

Glucokinase in the liver

Answer 6

excess glucose flows to liver for energy storage; production of glycogen and fatty acid synthesis

Question 7

What does glucokinase do in pancreatic cells?

Answer 7

acts as a glucose sensor to stimuate insulin release

Question 8

Phosphofructokinase-1

Answer 8

Controls glycolytic flux

Question 9

What are PFK-1’s inhibitors and activators?

Answer 9

Activators: AMP, ADP, F-2,6-BP; signal low energy charge
Inhibitors: ATP, Citrate, PEP; signal high energy charge

Question 10

Describe the allosteric regulation of PFK-1 in terms of energy charge

Answer 10

High energy charge; more ATP, T state dominant = inactive
Low energy charge; more AMP and ADP; R state dominant = active