Book 2

Book 2

Cells, tissues and organs
Organisms in the environment
Enzymes
1. Proteins, catalysts and enzymes
  1. Enzymes
    1. Biological catalysts - speed up reactions
    2. Large proteins shape is vital for functionas has an area where other molecules can fit - active site
    3. Substrate can be held on active site and either be connected to another molecule or broken down
    4. Can
      1. Build large molecules from smaller ones
      2. Change one molecule into another one eg convert one type of sugar into another
      3. Break down large molecules into smaller ones
  2. Protein
    1. Made of long chain amino acids
    2. Shape of a protein depends on its function
    3. Can be:
      1. Structural components of tissues, such as muscles
      2. Hormones
      3. Antibodies
      4. Catalysts
2. Factors affecting enzyme action
  1. Ractions take place faster at higher temperatures as molecules move around quickly so collide with each other more often and with more energy
  2. If temperatures gets too hot aciive site changes shape enzymne becomes denatured
Energy from respiration
1. Aerobic respiration
  1. glucose + oxygen > carbon dioxide + water (+energy)
  2. Energy used:
    1. Build molecules from smaller ones
    2. Enable muscle contraction in muscles
    3. Maintain a constant body temperature in colder surroundings in mammals and birds
    4. Build sugar, nitrates and other nutrients into amino acids and then proteins in plants
  3. Investigation used is masuring volume of carbon dioxide limewater is used to detect carbon dioxidie. The quicker the limewater turns cloudy the faster the faster carbon dioxide is being produced. If germinating peas are left in a thermos flask, the rise in temperature due to respiration can be monitored
2. Effect of excercise on the body
  1. Heart and breathing rate increase depth of breath increase
  2. Blood vessels supplying the muscles dilate (widen)
  3. Glycogen can be converted back to glucose for use during excercise
3. Anaerobic respiration
  1. Muscles use anaerobic respiration if they are short of oxygen as they have been worked too hard
  2. When muscles respire anaerobically they build up an oxygen debt
  3. Glucose not completely broken down and lactic acid produced one cause of muscle fatigue
  4. Less energy is released form the glucose
  5. Blood flowing through the muscles removes the lactic acid through secondary reaction

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