Respiration

• Respiration


  The release of energy from food
• The food involved in respiration is usually glucose
• Internal respiration


  Controlled by enzymes which allow energy to be released in small amounts
• Energy


  Trapped in molecules called ATP
• Types of Respiration


  • Aerobic Respiration
  • Anaerobic Respiration
• Aerobic Respiration


  The release of energy from food in the presence of oxygen
• Anaerobic Respiration


  The release of energy from food without requiring the presence of oxygen
• Aerobes


  • Most living things get energy from aerobic respiration
• ATP


  Supplies energy for all the reactions in a cell such as movement of muscles, growth of new cells etc.
• Aerobic Respiration


  Glucose + Oxygen -> Carbon dioxide + water + energy
• Aerobic respiration efficiency


  40% of the energy in glucose is used to make ATP, any energy not used to produce ATP is lost as heat

  
• Glycolysis


  The first stage of respiration that takes place in the cytosol, does not require oxygen, and only releases small amounts of energy

  
• Glycolysis is the same for both aerobic and anaerobic respiration
• Glycolysis


  1. A 6 carbon carbohydrate (Glucose) is converted to two 3 carbon-molecules called pyruvate with the release of a small amount of energy

  2. 2 ATP molecules are formed from ADP by Phosphorylation

  3. 2 NADH molecules are formed from NAD+

  
• Kreb cycle


  1. Pyruvic acid enters mitochondria by active transport under aerobic conditions

  2. Pyruvic acid becomes reduced to form acetyl Coenzyme A (2 carbon molecule) and CO2 is given off

  3. Acetyl CoA enters the Krebs cycle

  4. The Krebs cycle is a cycle in which CO2, ATP, water and NADH are formed

  5. NADH formed goes toward electron transport system

  6. CO2 and water diffuse out of the blood

  
• Electron Transport System


  Occurs in the cristae of the mitochondria, NADH (from Krebs' cycle) releases high energy electrons to a series of protein molecules which are passed from molecule to molecule along the system, the electrons lose/release energy which is used to form ATP from ADP and any energy left is lost as heat, 38 ATP are produced in this stage, the low energy electrons combine with oxygen and hydrogen to form water

  
• Anaerobic respiration can occur in the presence of oxygen but it does not need to use it
• Anaerobes


  Organisms that get their energy using anaerobic respiration, e.g. anaerobic bacteria does not require oxygen to survive
• Anaerobic respiration


  Less efficient than aerobic respiration as less energy is released
• The Krebs cycle occurs in the mitochondrion matrix during the second stage of respiration, requires oxygen, starts with acetyl Co-enzyme A, releases carbon dioxide, protons (H+) and energised electrons

  
• The electron transport chain is located in the cristae of mitochondria, requires oxygen, starts from NADH, accepts and carries protons (H+) and electrons, allows electrons to release energy to form ATP from ADP, formation of water at the end

  
• Acetyl co.enzyme A is formed from pyruvic acid (C3), is a 2 carbon molecule, is produced in mitochondria, starts the Kreb cycle

  
• Glycolysis is the first stage of respiration, occurs in the cytosol, is oxygen independent, happens in anaerobic respiration, begins with glucose (C6), produces pyruvic acid (3 carbon molecule), yields low energy

  
• NADH is a high energy molecule formed from NAD+, high energy electrons and a proton (H+), captures and carries proton (H+) and electrons to the electron transport chain in the cristae of mitochondria

  
• Fermentation


  Anaerobic respiration
• Types of Fermentation


  • Lactic Acid Fermentation
  • Alcohol Fermentation
• Lactic Acid Fermentation


  Glucose -> 2 Lactic Acid + small amount of energy

  
• Lactic Acid Fermentation


  • Bacteria causing milk to go sour
  • Bacteria respiring on cabbage to form Sauerkraut
  • Silage production
  • Yoghurt production
  • Anaerobic respiration in muscles during exercise

  
• Alcohol Fermentation


  Glucose -> 2 Ethanol + 2 Carbon dioxide + small amount of energy

  
• In the experiment to demonstrate fermentation (anaerobic respiration) in yeast, the glucose solution is boiled to remove oxygen, covered with oil to prevent oxygen entering, and kept at 30 degrees Celsius for 48 hours until no more carbon dioxide is produced

  
• In the experiment, the enzyme is yeast, the substrate is glucose, and the products are alcohol and carbon dioxide

  
• Testing for Alcohol


  1. Iodoform Test: Add sodium hypochlorite and potassium iodide, warm and observe yellow crystals

  2. Testing for Carbon Dioxide: Add limewater and observe it turning milky
• Biotechnology


  The use of living things (such as microorganisms and enzymes) to carry out useful reactions
• Bioreactor


  The vessel in which biological reactions can take place
• In industrial fermentation, foam may be formed so a foam breaker is used, oxygen is pumped in through a sparger, and the quality and amount of product depend on the quality of the microorganism and substrate, the design of the bioreactor, a correct rate of mixing, a correct temperature and pH and elimination of contaminating microorganisms
• Microorganisms used in bioprocessing

  • Bacteria
  • Fungi (especially yeast strains)
• Immobilised cells


  Microorganisms used in a bioreactor that are bonded to each other, bonded to an insoluble support, or suspended in a gel or membrane to ensure they are not lost at the end of every reaction
• Uses of Immobilised Cells/Microorganisms

  • Bacteria and fungi attached to sand and gravel to decompose waste in sewage treatment
  • Yeast cells immobilised with sodium alginate in alcohol production
• Advantages of Immobilised Cells

  • Immobilisation is gentle and does not damage cells
  • Immobilised cells can be easily recovered
  • Immobilised cells reduce the need for filtration at the end of bioprocessing
  • Immobilised cells can be reused reducing costs
• Differences between Aerobic and Anaerobic Respiration

  • Location: Cytoplasm and Lumen and Cristae of mitochondria vs Cytoplasm
  • Oxygen Requirements: Uses O2 vs Does not use O2
  • End Products: CO2 + H2O vs Ethanol +CO2 or Lactic acid
  • Energy Produced: Lots of energy (38 ATP) vs Little energy (2 ATP)