Energy production : carbohydrate 3

Question 1

What is allostery?

Answer 1

activator/inhibitor binds at another site

allo = other

steric = site

Question 2

What are the two sites on protein and name the ligands that bind to them

Answer 2

• Catalytic site : substrate
• Regulatory site : regulatory molecule

Question 3

What is covalent modification?

Answer 3

• Addition or removal of chemical gorup
• alters protein structure and function

Question 4

What are the types of regulation in metabolic pathway?

Answer 4

• Product inhibition
• Committing step inhibition
• hormonal regulation
• feed forward

Question 5

How does product inhibition occur in metabolic pathway regulation?

Answer 5

• Feedback inhibition
• Allosteric inhibition by end product of pathway on first enzyme in pathway
  
  • reduced entry of substrate and build up

Question 6

What activates and inhibits catabolic pathway?

Answer 6

(+) : Low energy signals, ADP, AMP, NAD+, FAD

(-) : High energy signals, ATP, NADH, FAD2H

Question 7

What is feed forward regulation?

Answer 7

Early pathway substrate provides allosteric signal to stimulate a later enzyme to activate pathway

Question 8

Give examples of phosphoregulation

Answer 8

• Adrenaline
  
  • Activates PKA
  • phosphorylation activates Phosphorylase kinase
  • phosphorylation of glycogen phosphorylase - stimulates glycogen breakdown
• Insulin
  
  • activates protein phosphatase 1
  • dephosphorylates(activaes) pyruvate dehydrogenase - stimulates glucose utilisation
  • dephosphorylates glycogen phosphorylase - inhibits glycogen breakdown

Question 9

What is the key regulator of glycolysis?

Answer 9

Phosphofructokinase-1

Question 10

What regulations is PFK involved in?

Answer 10

• Allosteric regulation
  
  • inhibited by high ATP
  • stimulated by high AMP
• Hormonal regulation
  
  • inhibited by glucagon
  • stimulated by insulin
• Metabolic regulation
  
  • High [NADH] - high energy levels
  • causes product inhibition

Question 11

What are the signals for PFK?

Answer 11

• (+)
  
  • AMP, F2,6-BP, insulin
• (-)
  
  • ATP, PEP, Citrate, H+ , Glucagon

Question 12

What regulation is pyruvate kinase involved in?

Answer 12

Hormonal regulation

Question 13

What are the signals for Pyruvate kinase?

Answer 13

• (+)
  
  • Insulin
• (-)
  
  • Glucagon

Question 14

What regulation is hexokinase involved in?

Answer 14

• Metabolic regulation
  
  • product inhibition by G-6-P