A110 Lesson 5: The Cytosol - Glycogen Metabolism

Flashcards on Glycogen Metabolism

Glycogen

A storage form of glucose, primarily in the liver and muscles.

Glycogenesis

The synthesis of glycogen from glucose monomers.

Glycogenolysis

The breakdown of glycogen into glucose monomers.

Slow-Twitch Fibers

Muscle fibers rich in myoglobin, have high endurance, and rely on oxygen for energy.

Fast-Twitch Fibers

Muscle fibers with less myoglobin, are more glycolytic, and are suited for quick bursts of energy and power.

ATP

An unstable molecule that easily breaks down to form ADP and inorganic phosphate (Pi), releasing energy; constantly regenerated through cellular respiration.

GLUT (Glucose Transporter)

Proteins that facilitate the movement of glucose into and out of cells, following its concentration gradient.

Hexokinase

An enzyme that quickly adds a phosphate group to glucose, converting it into glucose-6-phosphate (G6P), trapping glucose inside the cell.

Glycogen

A highly-branched carbohydrate polymer made up of glucose units linked together by α-1,4-glycosidic and α-1,6-glycosidic bonds.

Glycogen granules

Stored form of glucose in cells, large and cannot easily diffuse out of the cell.

UDP-Glucose Pyrophosphorylase

Enzyme involved in the activation of glucose for incorporation into glycogen.

Glycogen Synthase

Enzyme that catalyzes the elongation of glycogen chains by adding glucose residues.

Glycogen Branching Enzyme (GBE)

Enzyme that creates branches in glycogen by forming α-1,6-glycosidic bonds.

Glycogen Phosphorylase

Enzyme that cleaves α(1→4)-glycosidic bonds during glycogenolysis, releasing glucose-1-phosphate.

Debranching Enzyme

Enzyme with 4:4 transferase and 1:6 glucosidase activity, involved in glycogen breakdown.

Glucose-6-Phosphatase

Enzyme present in the liver that allows it to release free glucose from glycogen stores.

Insulin

Hormone that promotes glucose uptake from the blood and stimulates glycogen formation.

Glucagon

Hormone that stimulates the breakdown of glycogen.

Glycogen Storage Diseases

Disorders caused by defects in enzymes associated with glycogen metabolism.