cg. 12 Respiration

• External Respiration - the process of gas exchange and or breathing. e.g. gas exchange in the stomata of leaves.
• Internal Respiration - the controlled release of energy from glucose
• Internal respiration is controlled by enzymes, therefore pH and temperature affect it (plants go to hibernation due to slow respiration)
• ATP - Adenosine Triphosphate
• Aerobic Respiration - the controlled release of energy from glucose using oxygen.
• Living things that get their energy from Aerobic Respiration are called Aerobes
• ATP (Adenosine Triphosphate) provides energy for all metabolic reactions in the cell, e.g. muscle movement, mitosis and growth.
• Aerobic respiration is the most effective way of obtaining energy as glucose is being fully broken down
• The end products of aerobic respiration (carbon dioxide and water) have low energies, which if not used will break down as heat, e.g. body heat - carbon dioxide being exhaled as warm breath and water being released as sweat or tears.
• Balanced Equation of Aerobic Respiration

  C6H12O6 + 6O2 → 6CO2 + 6H2O  (glucose + oxygen -> carbon dioxide + water)

  enzymes on top of arrow
• anaerobic respiration - is the controlled release of energy from glucose without the use of oxygen.
• Anaerobic Respiration is also known as fermentation:

  • does not use oxygen
  • it is a stage 1 process (glycolysis)
  • takes place in the Cytosol
  • releases a small amount of energy
  • breaks down glucose into pyruvate
• anaerobic respiration is less effective than aerobic respiration as the glucose is only being partially broken down
• Two common Types of Fermentation are:

  • Lactic Acid Fermentation (muscle)
  • alcohol fermentation (yeast)
• Lactic Acid Fermentation

  • occurs when some human muscle is short on oxygen
  • pyruvate is converted to lactic acid
  • lactic acid builds up in muscle causing cramping and stiffness
  • when the person gets oxygen back into their body and rests, the lactic acid is taken to the liver by the blood and broken down
• Word Equation for Lactic Acid Fermentation

  glucose -> lactic acid + small amount of energy
• Alcohol Fermentation

  • takes place in fungi (yeast)
  • occurs when yeast is deprived of oxygen
  • pyruvate is converted into ethanol and carbon dioxide
  • ethanol is a high energy product
• Lactic Acid - when bacteria act on dairy products to make cheese and yoghurt

  Alcohol Fermentation - yeast is mixed with flour and liquid to form dough, when it comes into contact with heat, alcohol fermentation occurs, alcohol evaporates but C02 causes dough to rise
• Stage 1 - Glycolysis

  glycolysis - is the conversion of glucose into two molecules of pyruvate

  • takes place in the cytosol
  • is anaerobic
  • forms a small amount of ATP
  • end product is pyruvate
• Stage 2

  If oxygen is present, pyruvate (has three carbon molecules, 3c) enters the mitochondria, where it loses a carbon dioxide molecule to form a two-carbon molecule called Acetyl CoA

  Pyruvate also loses two hydrogens, these combine with NAD (carrier molecule) to form NADH.
• Krebs Cycle

  Acetyl CoA now enters into a series of reactions called Krebs Cycle, which occurs in the Lumen of the mitochondria.

  Here, Acetyl CoA is broken down into carbon dioxide and hydrogens.

  These Hydrogen electrons are picked up by NAD to form NADH.

  NADH molecules enter the electron transport system

  At one point in the Krebs Cycle, a single ADP & phosphate is converted to ATP and water.
• Electron Transport System

  The electron transport system is located on the inner membrane of the mitochondria. Infoldings of the inner membrane increase the surface area. High energy electrons are passed from NADH. As the electrons pass from molecule to molecule with each system, they lose some of their energy. This energy released by the electrons are formed into ATP. The rest of the energy is lost as heat. Low energy electrons combine with oxygen and hydrogen protons to form water.
• Biotechnology - is the use of living things or their components to manufacture useful products or to carry out useful reactions
• Bioreactor - is a vessel or container in which living things or their enzymes are used in to make a new product
• Experiment - the production of alcohol by yeast

  • prepare glucose solution (substrate)
  • boil solution to eliminate oxygen which creates anaerobic conditions
  • add yeast
  • Cover the liquid in the flask with oil (prevents oxygen from re-entering solution)
  • fermentation lock is used to prevent micro-organisms entering & allows carbon dioxide to pass out
  • lime water in f.lock to prove the presence of carbon dioxide (turns cloudy)
  • apparatus placed in 25 degrees hot plate
  • bubbles of C02 forms, when they stop forming, fermentation is complete, meaning yest has used up all glucose
• experiment - Show the production of ethanol

  • filter solution
  • place filtrate into test tube
  • add equal volume of potassium iodide solution
  • add few drops of soium hypochlorite (solution turns brown/orange)
  • place in water bath at 50 - 60 degrees
  • appearance of pale yellow crystals in clear solution proves presence of ethanol
• what does ATP convert to once it has release energy?

  ADP + Phosphate + Small amount of energy