Chapter 24

These flashcards cover key concepts related to glycogen degradation, its enzymatic processes, and regulation mechanisms necessary for exam preparation.

What is glycogen primarily used for in animal cells?

Glycogen is a polymer of glucose used to store energy.

What are the two types of glycosidic bonds found in glycogen?

α-1,4 bonds create linear chains, while α-1,6 bonds generate branches.

What is the role of glycogen phosphorylase in glycogen degradation?

It cleaves glycogen at non-reducing ends, releasing glucose 1-phosphate.

What is the product of glycogen phosphorylase action?

The product is glucose 1-phosphate.

What determines the activity of glycogen phosphorylase?

Activity is modified by phosphorylation and allosteric regulators.

What is the difference between phosphorylase a and phosphorylase b?

Phosphorylase a is more active and phosphorylated, while phosphorylase b is less active and not phosphorylated.

What is the function of phosphoglucomutase?

It converts glucose 1-phosphate to glucose 6-phosphate.

What is the significance of glucose 6-phosphatase in the liver?

It dephosphorylates glucose 6-phosphate to glucose for transport out of the cell.

How do ATP and AMP affect glycogen phosphorylase activity in muscle?

ATP and glucose 6-phosphate stabilize the T-state (inactive), while AMP stabilizes the R-state (active).

What hormones regulate glycogen degradation, and what are their effects?

Glucagon stimulates glycogen breakdown in the liver, while epinephrine stimulates breakdown in muscle tissue.

What is Hers disease?

A hereditary disorder of glycogen metabolism caused by mutations in the liver isozyme of glycogen phosphorylase.

How do glucagon and epinephrine affect glycogen phosphorylase?

They regulate its phosphorylation state via a receptor cascade, promoting glycogen breakdown.

What types of organisms utilize glycolysis and gluconeogenesis?

Eukaryotes, including animals, use these pathways for energy and glucose regulation.

What enzyme hydrolyzes α-1,6 linkages during glycogen degradation?

α-1,6-glucosidase (debranching enzyme) hydrolyzes these linkages.

What is the role of transferase in glycogen degradation?

Transferase moves three glucose residues from one branch terminus to another for complete degradation.