Overview
This lecture covers glycolysis, focusing on its process, location, energy yield, and key steps, including ATP and NADH production.
Glycolysis Overview
- Glycolysis breaks 1 glucose (C6H12O6) into 2 pyruvate (3 carbons each).
- Glycolysis has two phases: energy investment and energy payoff.
- The overall net ATP gain from glycolysis is 2 ATP.
- 2 ATP are spent in early steps, 4 ATP are produced in later steps.
- Glycolysis occurs in the cytoplasm of cells.
Significance and Conditions
- Glycolysis is anaerobic; it does not require oxygen.
- It provides some energy during low-oxygen situations like intense exercise or low-oxygen environments.
- Most cellular ATP comes from mitochondria, but glycolysis provides about 5% of total ATP.
Key Steps and Enzymes
- The first step uses the enzyme hexokinase to convert glucose to glucose 6-phosphate.
- Adding phosphate traps glucose inside the cell, ensuring it stays for energy use.
- Kinases are enzymes that add phosphate groups to molecules.
Outputs and Electron Carriers
- Glycolysis produces 2 ATP (net) and 2 NADH per glucose.
- NADH is an electron carrier; each NADH can yield around 3 ATP during later aerobic steps.
- The 2 NADH formed in glycolysis can generate 6 more ATP if oxygen is present.
Key Terms & Definitions
- Glycolysis — metabolic pathway splitting glucose into two pyruvate molecules.
- Cytoplasm — the fluid inside cells where glycolysis takes place.
- ATP (Adenosine Triphosphate) — primary energy currency of the cell.
- Anaerobic — a process that does not require oxygen.
- Hexokinase — enzyme that adds phosphate to glucose, forming glucose 6-phosphate.
- Kinase — enzyme that adds phosphate groups to other molecules.
- NAD/NADH — electron carrier; NAD gains electrons/hydrogens to become NADH.
Action Items / Next Steps
- Review the two phases of glycolysis and their respective ATP changes.
- Learn the function of hexokinase and why glucose 6-phosphate is important.
- Be able to explain glycolysis’ significance in anaerobic energy production.