Glycogen Synthesis and Regulation

This set of flashcards covers key vocabulary and concepts related to glycogen synthesis and regulation, as well as associated metabolic disorders.

What reaction does UDP catalyze in glycogen synthesis?

UDP catalyzes the transfer of glucose to glycogen, aiding in glycogen formation.

What are the substrate requirements for glycogen synthase?

Glycogen synthase requires UDP-glucose as a substrate for glycogen synthesis.

What is the role of UDP in glycogen synthesis?

UDP provides the glucose necessary to extend the glycogen chain during synthesis.

What three enzymatic activities are necessary to synthesize glycogen?

The three activities are: 1) Glycogen synthase, 2) branching enzyme, and 3) glycogenin.

What is the cost of making glycogen?

The synthesis of glycogen costs energy in the form of ATP and GTP, which are used to convert glucose-6-phosphate into UDP-glucose.

What hormones regulate glycogen synthase?

Insulin enhances glycogen synthase activity, while glucagon and epinephrine inhibit it.

What is the mechanism of regulation of glycogen synthase?

Glycogen synthase is activated when dephosphorylated by insulin and inhibited when phosphorylated by glucagon or epinephrine.

How do blood-glucose levels coordinate regulation of phosphorylase and synthase in the liver?

High blood-glucose stimulates insulin release, activating glycogen synthase and inhibiting glycogen phosphorylase; conversely, low blood-glucose triggers glucagon release, which activates phosphorylase and inhibits synthase.

What defects occur in type 1 and type 2 diabetes, McArdle disease, and Hers disease?

Type 1 diabetes involves insulin deficiency, type 2 diabetes involves insulin resistance; McArdle disease affects muscle's ability to break down glycogen, while Hers disease affects liver glycogen breakdown.

How does this compare to energy obtained from oxidizing glucose?

Glycogen metabolism provides quick access to glucose for energy, while oxidizing glucose generates more ATP through cellular respiration.