Lecture Notes on Anaerobic Energy Production and Fermentation

Understanding Anaerobic Respiration

Oxygen's Role: Oxygen serves as the final electron acceptor in oxidative phosphorylation during chemiosmosis. Without oxygen, the electron transport chain (ETC) cannot function, leading to the absence of a gradient.
Anaerobic Conditions: When oxygen is absent, organisms switch to anaerobic processes such as fermentation.

Process:
- Begins with glycolysis (glucose to pyruvate, producing NADH and a bit of ATP).
- In the absence of oxygen, pyruvate is reduced to lactate while NADH is oxidized to NAD+.
- This allows glycolysis to continue by regenerating NAD+.
Example:
- Human muscles during intense exercise (e.g., running hard) experience lactic acid buildup causing muscle soreness, but it allows survival in low oxygen situations.

Process:
- Similar start as lactic acid fermentation with glycolysis.
- Pyruvate is reduced to ethanol and CO2 is released, regenerating NAD+ from NADH.
- Common in yeast, contributing to bread rising and alcohol production.

Anaerobic Process: Occurs in the absence of oxygen, essential for regenerating NAD+ to allow continued ATP production via glycolysis.
Applications:
- Production of dairy products (cheese, yogurt) through bacterial lactic acid fermentation.
- Alcoholic beverages and leavened bread through yeast fermentation.

Biomolecules: Not just glucose in our diet, includes proteins, carbohydrates, nucleic acids, and lipids.
Digestion Process:
- Proteins: Broken down into amino acids.
- Carbohydrates: Broken down into monosaccharides.
- Nucleic Acids: Broken down into nucleotides.
- Lipids: Triglycerides broken down into glycerol and fatty acids.
Metabolic Pathways: Different monomers enter cellular respiration at different stages depending on their structure.
Example: Amylase in saliva begins carbohydrate digestion resulting in sweet taste of monosaccharides.

Fermentation is crucial for energy production in anaerobic conditions by regenerating NAD+.
Different pathways for lactic acid and alcohol fermentation based on the organism and conditions.
Digestion breaks down complex biomolecules into monomers that enter various stages of cellular respiration.

The lecture provided insights into alternative energy production processes when oxygen is scarce, and the metabolic pathways of different biomolecules following digestion.