Control Of Glycogen Metabolism Wk3

Question 1

Different pathways for breakdown and synthesis of glycogen = fine control

Answer 1

Halogen phosphorylase (catabolism)
Glycogen synthase (anabolism)

Question 2

Opposing pathways of glycogen synthesis and degradation

Question 3

Muscle and liver are main glycogen stores

Question 4

Two diff types of control

Answer 4

Allosteric binding of cofactor at non-catalytic site = affecting enzyme conformation
Covalent modification formation of covalent bonds that alter chemistry of enzyme

Question 5

Allosteric control glycogen phosphorylase

Answer 5

Activated by AMP (signals need for glucose breakdown)
Inhibited by ATP and G6P (indicate high energy)

Question 6

Glycogen synthase

Answer 6

Activated by G6P (excess GP6 signals storage for future need

Question 7

Covalent modification
Phosphorylation and de phosphorylation provides a sensitive control mechanism

Answer 7

Glycogen phosphorylase activated by phosphorylation, inhibited by dephosphorylation
Glycogen synthase activated by dephosphorylation; inhibited by phosphorylation

Question 8

Reciprocal regulation

Answer 8

Glycogen phosphorylase

Glycoge synthase

Question 9

Control Cascade - glycogen catabolism

Question 10

cAMP turns off PP system

Question 11

Hormonal signals & glycogen metabolism

Answer 11

Liver: low blood sugar
Signal: glucagon released from pancreas
Binds to g-coupled glucagon receptor (liver)