🧬

bio edpuzzle 7.3

Jul 28, 2025

Overview

This lecture explains anaerobic cellular respiration, focusing on the processes and significance of glycolysis and fermentation in the absence of oxygen or mitochondria.

Cellular Respiration Overview

  • Aerobic respiration uses glucose, glycolysis, the Krebs cycle, electron transport chain, and requires mitochondria and oxygen.
  • Glycolysis breaks down glucose to pyruvate, netting 2 ATP.
  • Krebs cycle produces 2 more ATP and releases COâ‚‚.
  • Most ATP (32-34) is generated in the electron transport chain with oxygen as the final electron acceptor.

Anaerobic Cellular Respiration

  • Occurs when there is no oxygen or no mitochondria.
  • Consists of glycolysis followed by fermentation.
  • Glycolysis alone cannot continue without regenerating NAD+ from NADH.
  • Two types of fermentation: lactic acid fermentation and alcoholic fermentation.

Lactic Acid Fermentation

  • Performed by animals and some bacteria after glycolysis.
  • Pyruvate is converted into lactate (lactic acid), regenerating NAD+ for continued glycolysis.
  • No additional ATP is produced in fermentation; ATP comes only from glycolysis.
  • Builds up lactate in muscles during intense exercise, causing pain and fatigue.
  • Lactate is later broken down using oxygen after exercise.
  • Bacteria use lactic acid fermentation to make products like yogurt.

Alcoholic Fermentation

  • Occurs in yeast and some bacteria.
  • Pyruvate is converted into ethyl alcohol (ethanol) and COâ‚‚, regenerating NAD+.
  • Used in brewing and baking; alcohol accumulation eventually kills the yeast.
  • COâ‚‚ produced causes bubbles in beer, champagne, and bread.

Key Terms & Definitions

  • Anaerobic respiration — cellular respiration that occurs without oxygen or mitochondria.
  • Glycolysis — first step in breaking down glucose to pyruvate, netting 2 ATP.
  • Fermentation — process that regenerates NAD+ from NADH, allowing glycolysis to continue in anaerobic conditions.
  • Lactic acid fermentation — fermentation process producing lactate and regenerating NAD+.
  • Alcoholic fermentation — fermentation producing ethanol and COâ‚‚ while regenerating NAD+.

Action Items / Next Steps

  • Review related lecture/videos on aerobic respiration, mitochondria, and associated processes as needed.

Full transcript