Glycolysis Lecture Notes

Introduction to Glycolysis

• Glycolysis is the process of breaking down glucose to produce energy.
• The lecture covers the transformation from consuming a doughnut to energy production.
• Discussion of pyruvate, lactate, and their roles in bioenergetics.

Digestion and Blood Sugar

• Digestion of a doughnut leads to glucose formation.
• Glucose is also referred to as blood sugar or blood glucose in the bloodstream.
• Pathways for glucose:
  • Remains in the blood.
  • Short-term storage as glycogen in muscles/liver.
  • Long-term storage as fat.

Glycolysis Process

• Glycolysis uses blood sugar from carbohydrates.
• Occurs in the cytoplasm of cells and does not require oxygen (anaerobic).
• The environment determines the end product (pyruvate or lactate).

Anaerobic Glycolysis

• Occurs under high activity levels (e.g., sprinting).
• Glucose (6-carbon) is split into two pyruvate (3-carbon) molecules.
• Pyruvate converts to lactate in anaerobic conditions.
• Lactate production turns NADH into NAD+.
• Lactate can accumulate in the blood, leading to lactate threshold issues.

Cori Cycle

• Lactate can be converted back to glucose in the liver (gluconeogenesis).
• Gluconeogenesis involves converting byproducts like lactate back to glucose.
• Other molecules like amino acids and fats can also undergo gluconeogenesis.

Aerobic Glycolysis

• Occurs when there is sufficient oxygen (e.g., jogging, walking).
• Follows the same initial steps as anaerobic: glucose to pyruvate.
• Pyruvate enters the Krebs Cycle in the presence of oxygen.
• Pyruvate's carbon combines with oxygen to form CO2, released via exhalation.
• Acetyl-CoA, a 2-carbon molecule, enters the Krebs Cycle for further energy extraction.

Energy Yield

• Glycolysis yields a net gain of 2 ATP per glucose molecule.
• Involves initial investment of 2 ATP and production of 4 ATP.
• Enzymes speed up glycolysis, with phosphofructokinase (PFK) as a key rate-limiting enzyme.

Conclusion

• Without oxygen, glycolysis ends in lactate production.
• With oxygen, the process continues into the Krebs Cycle and oxidative phosphorylation.
• Suggested further learning on the Krebs Cycle and oxidative phosphorylation.

Additional Information

• Encouragement to subscribe for more educational content on bioenergetics.