4.1 - Introduction to Cellular Respiration and Fermentation

• There are three stages of cellular respiration: glycolysis, the Krebs cycle (also known as the citric acid cycle), and oxidative phosphorylation.
• The process by which glucose is broken down into carbon dioxide, water, and energy is called cellular respiration.
• Cellular respiration occurs in the mitochondria of eukaryotic cells or in prokaryotes such as bacteria.
• Anaerobic means without oxygen, while aerobic refers to processes that require oxygen.
• What is the unbalanced cellular respiration equation?

  Glucose + Oxygen -> Carbon dioxide + Water + Energy
• Aerobic Cellular Respiration - a process that uses oxygen to harvest energy from organic compounds

  • the process that extracts energy from food
  • used to make ATP
  • takes place in most eukaryotes and some prokaryotes
• Obligate Aerobe - an organism that must have oxygen to live (obligated to breathe)

  • humans, plants, animals, etc. all require oxygen to live and carry out cellular respiration
• Obligate Anaerobe - an organism that cannot survive in an environment with oxygen

  • some species of bacteria/microorganism cannot live in the presence of oxygen
• Cellular Respiration consists of 4 steps:

  1. Glycolysis
  2. Pyruvate Oxidation
  3. Citric Acid Cycle
  4. Electron Transport Chain/Oxidative Phosphorylation
• Glycolysis - splits glucose into 2 pyruvate molecules and releases energy ( used to make ATP)
• In each step of cellular respiration, small bits of energy is harvested and stored in the form of ATP
• Pyruvate Oxidation - pyruvate is oxidized to form Acetyl CoA
• Citric Acid Cycle - a cycle of reactions that produces ATP and energy carrier molecules
• Electron Transport Chain / Oxidative Phosphorylation: uses energy carrier molecules to make ATP
• What process(es) occur in the mitocchondira?

  Pyruvate Oxidation, Citric Acid Cycle, Electron Transport Chain and Oxidative Phosphorylation
• What process(es) happen in the cytosol?

  Glycolysis
• Mitochondria - cell organelle involved in the production of ATP (powerhouse of the cell)
• ETC and Oxidative Phosphorylation take place within the inner membrane of the mitochondria
• Citric Acid Cycle and Pyruvate Oxidation take place within the Matrix ( fluid inside inner membrane)
• Energy can also be extracted from food molecules using Anaerobic Respiration.
• Anaerobic Respiration - harvesting energy from food molecules without using oxygen

  • use other molecules as oxidizing agents
  • produce less energy
  • ex. alcohol fermentation - yeast feed on sugar molecules and produce ethanol as a by-product
• Glycolysis

  • occurs in cytosol (cytoplasm)
  • splits 1 glucose molecule into 2 pyruvate molecules
  • produces 2 ATP
  • produces 2 NADH (energy carrier molecules)