Organisation

• Some organisms contain loads of cells but how do all these cells end up making a working human or squirrel? The answer is organisation.
• Without organisation, they'd just make a meaty splod
• Large Multicellular Organisms


  Made Up of Organ Systems
• Building blocks of organisms

  • Cells
• Differentiation


  The process by which cells become specialised for a particular job
• Differentiation occurs during the development of a multicellular organism
• Levels of organisation


  • Cells
  • Tissues
  • Organs
  • Organ Systems
• Tissues


  • A group of similar cells that work together to carry out a particular function
  • Can include more than one type of cell
• Tissue types in mammals (e.g. humans)


  • Muscle tissue which contracts (shortens) to move whatever it's attached to
  • Glandular tissue which makes and secretes chemicals like enzymes and hormones
  • Epithelial tissue which covers some parts of the body, e.g. the inside of the gut
• Organs


  A group of different tissues that work together to perform a certain function
• Organ Systems


  A group of organs working together to perform a particular function
• Organs in the digestive system


  • Glands (e.g. pancreas, salivary glands) which produce digestive juices
  • Stomach and small intestine which digest food
  • Liver which produces bile
  • Small intestine which absorbs soluble food molecules
  • Large intestine which absorbs water from undigested food, leaving faeces
• Organ systems work together to make entire organisms
• Enzymes


  What make you work
• Enzymes


  • Catalysts produced by living things
  • Thousands of different chemical actions going on inside them all the time
  • Need to be carefully controlled to get the right amounts of substances
  • Speed up useful reactions but also the unwanted ones
  • Have a limit to how high the temperature can be raised before the cells start getting damaged
• Raising the temperature


  Speeds up the reaction
• Catalyst


  A substance which increases the speed of reaction without being changed or used up in the reaction
• Enzymes


  • Large proteins made up of chains of amino acids
  • Have unique shapes to catalyse reactions
  • Usually only catalyse one specific reaction
  • Need to have the substrate fit into their active site
• Enzyme action


  1. Substrate binding

  2. Active site changes shape to get a tighter fit (induced fit model)

  3. Catalysis

  4. Products released, enzyme unchanged
• Enzymes


  • Have an optimum temperature where they are most active
  • Have an optimum pH that they work best at
• Investigating Enzymatic Reactions


  You know how to invergate the effect of it on the role of ectoty
• The eye the breakdown of teesh to meltoe. I's easy to detect fach uning i
• The enzyme catalase catalyses the breakdown of hydrogen peroxide into water and oygen
• Amylase

  Enzyme that catalyses the breakdown of starch to maltose
• Investigating the effect of pH on amylase activity


  1. Put a drop of iodine solution into every well of a spotting tile

  2. Heat water to 35°C in a beaker on a tripod and gauze over a Bunsen burner

  3. Add 1cm³ amylase solution and 1cm³ buffer solution with pH 5 to a boiling tube, put in water bath for 5 minutes

  4. Add 5cm³ starch solution to boiling tube

  5. Immediately mix and start stop clock, take samples every 30 seconds and add to iodine solution in spotting tile

  6. Record time taken for starch to be broken down (no colour change with iodine)

  7. Repeat with buffer solutions of different pH values

  8. Control variables each time to make it a fair test
• Iodine solution


  • Changes from browny-orange to blue-black in presence of starch
• You could use a pH meter to accurately measure the pH of your solutions
• Rate of reaction


  Can be calculated from the time taken for the starch to be broken down
• Enzyme unit


  Catalyses the breakdown of starch to maltose
• Investigating the effect of pH on amylase activity

  1. Add amylase and buffer solution to boiling tube

  2. Add starch solution

  3. Mix and start timer

  4. Sample every 30 seconds and test for starch with iodine

  5. Repeat with different pH buffers
• Starch detection


  • Iodine solution changes from browny-orange to blue-black in presence of starch
• Temperature control


  • Use water bath or Bunsen burner and beaker to maintain 35°C
• Sampling


  • Use dropping pipette to take samples every 30 seconds
• Variable control

  • Concentration and volume of amylase solution
• You could use a pH meter to accurately measure the pH of your solutions
• Enzymes


  Produced by cells and then released into the gut to mix with food
• Digestive enzymes break down big molecules


  1. Break down big molecules like carbohydrates, proteins and fats into smaller molecules like sugars, amino acids, glycerol and fatty acids

  2. Smaller molecules can pass through the walls of the digestive system and be absorbed into the bloodstream
• Carbohydrases


  Convert carbohydrates into simple sugars
• Carbohydrases


  • Amylase
• Amylase


  Breaks down starch