Question

1.

A) What is the effect on glycogen synthase? And which factors control whether phosphorylation or dephosphorylation takes place.

B) How does insulin in the blood supply lead to the storage of glucose as glycogen via activated glycogen synthase in liver cells?

C) Compare how insulin and glucagon signal different blood glucose levels and their effects on glycogen breakdown, glycogen synthesis and glycolysis.

D) Compare the fates of glucose 6-phosphate from glycogen breakdown in liver and muscle

Answer 1

1. Glycogen synthase is an enzyme that catalyse the addition of UDP - glucose t glycogen growing chain.and phosphorylation and dephosphorylation of ATP depends on energy requirement. and in case of enzyme activation and deactivation phosphorylation activated the enzyme while dephosphorylation deactivated the enzyme, so they acts as switch on and off controllers.   

2. the insulin hormone promotes the uptake of glucose by cells and tissue for energy production (cellular respiration and metabolism). if the glucose concentration is still more in blood than its utilization, then insulin will initiate the glycogenesis (formation of glycogen in liver and muscles and it is stored in liver and muscles.

3. the insulin hormone increase the uptake of glucose and increases the energy production by promoting glycolysis and kreb's cycle. if glucose concentration is more than the utilization then it will be converted into glycogen. if the concentration of glucose in the blood goes below the normal concentration 70 mg/dL then the glucagon promote the breakdown of glycogen stored in muscles and liver, and release free glucose in the blood for utilization by body cells.

the glucose 6 phosphate generated during glycogen breakdown, is used in two ways

a. in glycolysis, glucose 6 phosphate will be convected in fructose 6 phosphate and subsequently will follow pathway o produce pyruvate.

b. in HMP pathway - glucose 6 phosphate is used for the synthesis of Ribulose 5 phosphate and later Ribose 5 phosphate , used in the synthesis of DNA, RNA NAD, FAD etc.

4.