Question

How does phosphorylation influence glycogen synthesis or degradation?

a. specific enzyme "phosphrylases" act on their specific substrate depending on the signals given.
1. Glycogen synthase is INACTIVATED when phosphorylated
2. Glycogen phosphorylase is ACTIVATED when phosphorylated
b. then extends the carbohydrate chain until the glucosyl chain is long enough to serve as a substrate for glycogen synthase.
c. Glycogenin is a protein that helps in the synthesis of new glycogen primer molecules
d. The protein to which glycogen is attached

Answer 1

Phosphorylation regulates glycogen metabolism by activating glycogen phosphorylase, which promotes glycogen breakdown, and inactivating glycogen synthase, which inhibits glycogen synthesis, therefore managing glucose availability during energy demands.

Step-by-step explanation:

The influence of phosphorylation on glycogen synthesis or degradation is a crucial aspect in the regulation of glucose levels in the body. When enzymes such as glycogen synthase and glycogen phosphorylase undergo phosphorylation, they experience changes in their activity. Phosphorylation of glycogen synthase results in its inactivation, which inhibits glycogen formation, whereas phosphorylation of glycogen phosphorylase leads to its activation, promoting the breakdown of glycogen into glucose-1-phosphate. This glucose can then be used for energy during the fight-or-flight response, facilitated by hormones such as adrenaline that increase cyclic AMP (CAMP) levels in cells.

In a state requiring energy, such as during stress or exercise, the activation of protein kinase A (PKA) through cAMP results in the phosphorylation cascade that activates glycogen phosphorylase, contributing to the immediate availability of glucose. Meanwhile, the synthesis of new glycogen is mitigated by the inactivation of glycogen synthase, ensuring that glucose is readily available for urgent metabolic needs rather than being stored.