Biochemistry S1

Question 2

What are the four ways glycolysis is regulated?

Answer 2

Substrate availability (glucose), covalent modification, enzyme concentration, allosteric regulation

Question 3

Glycolysis regulation: what are the rate limiting enzymes?

Answer 3

step 1 - hexokinase
step 3- phosphofructokinase (PFK)
step 10 - pyruvate kinase
(all the irreversible steps)

Question 4

What is the T1 configuration of GLUT proteins?

Answer 4

Open binding site to the outside to allow glucose molecules to enter

Question 5

What happens when glucose binds to GLUT proteins?

Answer 5

Causes a conformational change from T1 to T2

Question 6

What is the T2 configuration of GLUT proteins?

Answer 6

Binding site open to inside, releasing glucose into cell

Question 7

What are the types of GLUT proteins and where are they found?

Answer 7

• GLUT 1 - RBC
• GLUT 2 - liver/beta cells
• GLUT 4 - muscle cells/adipocytes

Question 8

How is pyruvate kinase covalently modified?
(regulation of glycolysis)

Answer 8

By phosphorylation
(active when phosphorylated)

Question 9

What effect does glucagon have on pyruvate kinase?

Answer 9

Causes phosphorylation, inactivating it

Question 10

What happens to pyruvate kinase when it is dephosphorylated?

Answer 10

It is more active

Question 11

how are concentration of rate limiting enzymes controlled?

Answer 11

by hormones
insulin - upregulates
glucagon - downregulates