Cellular Respiration 🧬

Importance

• Cellular respiration is the most important biochemical process as it allows us to extract energy from food (specifically glucose).

Key Components

• Glucose (C₆H₁₂O₆): Main source of energy.
• Oxygen (O₂): Needed for aerobic respiration.
• ATP (Adenosine Triphosphate): Energy currency of cells.

Chemical Equation

• Reactants: C₆H₁₂O₆ + 6 O₂
• Products: 6 CO₂ + 6 H₂O + ATP (energy)

Process Overview

1. Glycolysis

   • Splits glucose (6 carbons) into two 3-carbon molecules called pyruvate.
   • Occurs in the cytoplasm.
   • Produces 2 net ATP and 2 NADH.
   • Anaerobic process (does not require oxygen).

2. Krebs Cycle (Citric Acid Cycle)

   • Occurs in the mitochondria.
   • Pyruvate is further broken down, producing CO₂, ATP, NADH, and FADH₂.
   • Produces 2 ATP.
   • Aerobic process (requires oxygen).

3. Electron Transport Chain (ETC)

   • Occurs in the inner mitochondrial membrane.
   • Uses NADH and FADH₂ to produce ATP via oxidative phosphorylation.
   • Produces about 34 ATP.
   • Aerobic process (requires oxygen).

Energy Yield

• Total ATP production can be up to 38 ATP from one molecule of glucose (ideal conditions).
• Actual yield might be around 29-30 ATP due to cell efficiency variations.
• Heat is produced as a byproduct, helping to maintain body temperature.

Fermentation (Anaerobic Respiration)

• Occurs when oxygen is absent.
• Produces lactate in humans (lactic acid fermentation).
• Produces ethanol in yeast and other organisms (alcoholic fermentation).

Summary

• Cellular respiration converts glucose into ATP.
• Involves three main stages: Glycolysis, Krebs Cycle, and Electron Transport Chain.
• Produces energy, CO₂, and water.
• Fermentation occurs under anaerobic conditions yielding much less ATP.

Important Terms

• NAD+ & NADH: Electron carriers, NADH produced during glycolysis and Krebs Cycle used in ETC.
• FAD & FADH₂: Another set of electron carriers involved in ETC.

In conclusion, cellular respiration is an essential process for energy production in living organisms, converting glucose into ATP through a series of stages requiring oxygen, producing both energy and heat as byproducts.