Glucólisis | Video HHMI BioInteractive

Understanding Glycolysis: The Energy Pathway

Overview of Glycolysis

• Glycolysis is the metabolic pathway that converts glucose into pyruvate, providing energy for living cells through a series of enzymatic reactions.

• Glucose from food is broken down slowly, yielding two molecules of pyruvate and extracting energy via glycolysis.

• ATP (adenosine triphosphate) serves as the primary energy source for cells, with mitochondria being the main organelles responsible for ATP production.

Enzymatic Steps in Glycolysis

• Enzyme 1: Hexokinase - Transfers a phosphate group from ATP to glucose, forming glucose-6-phosphate.

• Enzyme 2: Phosphoglucose Isomerase - Converts glucose-6-phosphate into its isomer, fructose-6-phosphate.

• Enzyme 3: Phosphofructokinase - Utilizes another ATP molecule to create fructose 1,6-bisphosphate.

Breakdown of Six-Carbon Sugar

• The six-carbon sugar is split by Enzyme 4: Fructose-Bisphosphate Aldolase, producing two three-carbon sugars with one phosphate each.

• Only glyceraldehyde-3-phosphate continues in glycolysis; dihydroxyacetone phosphate must be converted first.

Energy Capture Phase

• Enzyme 6: Glyceraldehyde 3-phosphate Dehydrogenase adds a second phosphate to glyceraldehyde-3-phosphate, forming 1,3-bisphosphoglycerate while reducing NAD+ to NADH.

• Enzyme 7: Phosphoglycerate Kinase transfers a phosphate from 1,3-bisphosphoglycerate to ADP, generating ATP.

Final Steps and Yield

• Subsequent enzymes rearrange and dehydrate the substrate before Enzyme 10: Pyruvate Kinase transfers the last phosphate group to ADP, producing another ATP and yielding pyruvate.