Glycogen Degradation

These flashcards cover key concepts related to glycogen degradation processes, enzymes involved, hormonal regulation, and physiological considerations.

Glycogen

A branched polymer of glucose residues used as a key energy source.

Glycogenolysis

The process of breaking down glycogen into glucose.

Glycogen phosphorylase

The key regulatory enzyme that cleaves glycogen to release glucose 1-phosphate.

Phosphorylase regulation

Controlled by allosteric interactions and reversible phosphorylation.

Allosteric effectors

Molecules that bind to an enzyme and alter its activity without changing the enzyme's concentration.

Epinephrine

A hormone that stimulates glycogen breakdown primarily in muscle.

Glucagon

A hormone that signals the need for glycogen breakdown, primarily affecting the liver.

Phosphorolysis

The cleavage of a bond by the addition of orthophosphate.

Enzymatic activities in glycogen breakdown

Includes glycogen phosphorylase, transferase, and debranching enzyme.

Debranching enzyme

An enzyme that hydrolyzes the bonds at branch points in glycogen.

Glucose 6-phosphate

An important metabolic intermediate derived from glucose 1-phosphate.

Phosphoglucomutase

An enzyme that converts glucose 1-phosphate into glucose 6-phosphate.

Liver vs. muscle glycogen

Liver glycogen is used to maintain blood glucose levels, while muscle glycogen serves immediate energy needs.

Glycogen granules

Small structures in the cytoplasm where glycogen is stored.

High gain system

A mechanism by which a small stimulus can lead to a large response in glycogen breakdown.

Type I muscle fibers

Slow-twitch fibers that primarily use fatty acids for energy and have low glycogen amounts.

Type IIb muscle fibers

Fast-twitch fibers that predominantly use glycogen for quick energy release.

Feedback inhibition

A process where an end product inhibits an earlier step in the pathway.

Isozymes

Enzymes that catalyze the same reaction but are different in structure and regulation.

Hungry state

Condition when glucagon is released due to low blood glucose levels.

Nocturnal fast

Period when the liver releases glucose to maintain brain function overnight.

Creatine phosphate

A high-energy compound used to quickly regenerate ATP in muscle cells.

McArdle’s disease

A glycogen storage disease caused by a deficiency in skeletal muscle glycogen phosphorylase.

Hers disease

A glycogen storage disorder caused by a deficiency in liver glycogen phosphorylase.

Calmodulin

A calcium-binding protein that plays a regulatory role in phosphorylase kinase activation.

Phosphorylation

The addition of a phosphoryl group to a molecule, often regulating enzyme activity.

Signal transduction cascade

A series of molecular events initiated by the binding of a signal molecule to a receptor.

cAMP

A second messenger that activates protein kinase A in response to hormones.

Glycogen saturation

The level of glycogen stored in muscle and liver relative to their capacity.

Glycolytic enzymes

Enzymes involved in the breakdown of glucose to produce energy quickly.

Phosphate release

The process of cleaving a phosphoryl group to generate free glucose from glucose 6-phosphate.

Muscle contraction

The process requiring energy from glucose, particularly during intense exercise.

Glycogen homeostasis

The balance of glycogen synthesis and breakdown to regulate glucose levels in the body.

Epinephrine signal response

The process by which epinephrine binding to receptors leads to glycogen mobilization.