Understanding Cellular Respiration Processes

Nov 17, 2024

Lecture Notes: Cellular Respiration

Introduction

  • Cellular Respiration vs. Breathing
    • Cellular respiration occurs at the cellular level, mainly inside mitochondria.
    • Requires oxygen to break down food and produce ATP.
    • Bacteria can perform respiration without mitochondria using their outer membranes.

Energy and Respiration in Sports

  • Cellular respiration provides energy (ATP) for muscle movement.
  • Study of world records shows pace drops off and stabilizes in longer distances.
  • Aerobic vs. Anaerobic Respiration
    • Aerobic Respiration: Requires oxygen; provides sustained energy.
    • Anaerobic Respiration: Used for quick bursts of speed; results in lactic acid buildup.

Respiration Process

  • Conducted by heterotrophs (animals, fungi, bacteria).
  • Converts organic compounds and oxygen into carbon dioxide, water, and ATP.
  • Autotrophs (plants, algae) convert carbon dioxide and water into organic materials.

Cellular Respiration Equation

  • Glucose + Oxygen → Carbon Dioxide + Water + ATP.
  • Energy resides in hydrogen outside glucose, transferred to oxygen.

Mitochondria Structure

  • Cristae: Folds on the inside.
  • Two membranes: Inner and outer.
  • Inner membrane space for proton buildup.
  • Mitochondria have characteristics of bacteria (DNA, ribosomes).

Stages of Cellular Respiration

  1. Glycolysis

    • Occurs in the cytoplasm, outside the mitochondria.
    • Breaks down glucose (6-carbon) into two pyruvate (3-carbon) molecules.
    • Produces 2 ATP and transfers electrons to NAD.

  2. Krebs Cycle

    • Converts pyruvate to acetyl CoA in the mitochondria matrix.
    • Acetyl CoA (2-carbon) enters the Krebs cycle.
    • Releases carbon dioxide and produces ATP, NADH, and FADH2.

  3. Electron Transport Chain

    • NADH and FADH2 transfer electrons through protein complexes.
    • Proton gradient created by pumping protons into the inner membrane space.
    • Oxygen acts as the final electron acceptor, forming water.
    • ATP synthase generates around 32 or 34 ATP from the proton gradient.

Alternative Pathways

  • Lactic Acid Fermentation
    • Occurs in muscles under stress; converts pyruvate to lactate.
    • Recycles NAD+ to continue glycolysis; results in lactic acid buildup.
  • Alcoholic Fermentation
    • Occurs in some bacteria and yeast; converts pyruvate to ethanol and carbon dioxide.
    • Recycles NAD+ to maintain glycolysis.

Applications

  • Cellular respiration can occur with various foods, not just glucose.
  • Plants, bacteria, and animals all perform cellular respiration to generate energy.

These notes summarize the key points of the lecture on cellular respiration, detailing the process, stages, and alternative pathways involved in the generation of energy at the cellular level.