Glycolysis

Glycolysis

The first stage of carbohydrate metabolism, occurring in the cytosol of all cells, converting glucose into pyruvate.

Cytosol

The liquid portion of the cytoplasm where glycolysis occurs.

Anaerobic

A process that does not require oxygen.

Net yield of glycolysis

2 ATP and 2 NADH per molecule of glucose.

NAD+

A coenzyme that must be regenerated from NADH to keep glycolysis running under anaerobic conditions.

Lactic acid (lactate)

The product formed when pyruvate is reduced to regenerate NAD+ under anaerobic conditions.

Lactate dehydrogenase

The enzyme that catalyzes the reduction of pyruvate to lactic acid.

Energy investment phase

The first phase of glycolysis (Steps 1-5) that consumes ATP.

Energy payoff phase

The second phase of glycolysis (Steps 6-10) that generates ATP.

Hexokinase

The enzyme that phosphorylates glucose to form glucose-6-phosphate.

Glucose-6-phosphate

The phosphorylated form of glucose resulting from hexokinase activity.

Glucosephosphate isomerase

The enzyme that converts glucose-6-phosphate to fructose-6-phosphate.

Fructose-6-phosphate

The product of glucose-6-phosphate isomerization.

Phosphofructokinase-1 (PFK-1)

The enzyme that catalyzes the phosphorylation of fructose-6-phosphate.

Fructose-1,6-bisphosphate

The product of the phosphorylation of fructose-6-phosphate by PFK-1.

Aldolase

The enzyme that cleaves fructose-1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.

Dihydroxyacetone phosphate (DHAP)

One of the two 3-carbon products formed from the cleavage of fructose-1,6-bisphosphate.

Glyceraldehyde-3-phosphate (G3P)

The other 3-carbon product formed from fructose-1,6-bisphosphate; continues in the glycolytic pathway.

Triose phosphate isomerase

The enzyme that converts DHAP into glyceraldehyde-3-phosphate.

Glyceraldehyde-3-phosphate dehydrogenase

The enzyme that oxidizes G3P to 1,3-bisphosphoglycerate.

1,3-bisphosphoglycerate

The product formed from the oxidation of G3P.

Free inorganic phosphate

The phosphate molecule utilized in the reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase.

NADH

The reduced form of NAD+; produced during glycolysis.

Phosphoglycerate kinase

The enzyme that transfers a phosphate group from 1,3-bisphosphoglycerate to ADP to form ATP.

3-phosphoglycerate

The product formed from the transfer of phosphate to ADP by phosphoglycerate kinase.

Substrate-level phosphorylation

The direct synthesis of ATP from ADP and a phosphorylated intermediate.

Phosphoglyceromutase

The enzyme that moves the phosphate on 3-phosphoglycerate to form 2-phosphoglycerate.

2-phosphoglycerate

The product formed by the action of phosphoglyceromutase.

Enolase

The enzyme that removes a water molecule from 2-phosphoglycerate to form phosphoenolpyruvate.

Phosphoenolpyruvate (PEP)

The product formed from the dehydration of 2-phosphoglycerate.

Pyruvate kinase

The enzyme that transfers the final phosphate group from PEP to ADP, generating ATP and pyruvate.

Thiamine pyrophosphate (TPP)

A cofactor derived from Vitamin B1 that assists in decarboxylation reactions.

Pyruvate decarboxylase

The enzyme that uses TPP to convert pyruvate during alcoholic fermentation.

Carbon dioxide (CO2)

The byproduct of decarboxylation reactions.

Gluconeogenesis

The process of synthesizing glucose from non-carbohydrate sources.

Lactate, amino acids, glycerol

Non-carbohydrate precursors utilized in gluconeogenesis.

Glycogenolysis

The process of breaking down glycogen into glucose.

Glucagon

A hormone secreted by the pancreas to increase blood glucose levels.

Insulin

A hormone that lowers blood glucose levels and stimulates glucose uptake in cells.

Glycogenesis

The conversion of glucose to glycogen for storage.

Metabolic Syndrome

A precursor condition characterized by impaired glucose response and increased risk of Type II diabetes.

Ketoacidosis

A potentially life-threatening condition characterized by high levels of ketone bodies due to insufficient insulin.

Sorbitol

A sugar alcohol formed from glucose that can accumulate in the eyes, leading to cataracts.

Hypoglycemia

A condition characterized by abnormally low blood glucose levels, often as a result of insulin treatment.