organisational

• Large Multicellular Organisms


  Made up of organ systems
• Cells are the basic building blocks that make up all living organisms
• Specialised cells


  Carry out a particular function
• Differentiation


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


  1. Cells

  2. Tissues

  3. Organs

  4. Organ systems
• Large multicellular organisms (e.g. humans) have different systems inside them for exchanging and transporting materials
• Tissue


  A group of similar cells that work together to carry out a particular function
• Tissues in mammals (like humans)


  • Muscular tissue
  • Glandular tissue
  • Epithelial tissue
• Organ


  A group of different tissues that work together to perform a certain function
• Tissues in the stomach


  • Muscular tissue
  • Glandular tissue
  • Epithelial tissue
• Organ system


  A group of organs working together to perform a particular function
• Organ systems work together to make entire organisms
• Enzymes


  Catalysts produced by living things that speed up chemical reactions
• Enzymes


  • They are large proteins made up of chains of amino acids folded into unique shapes
  • They have an active site with a unique shape that fits onto the substance involved in a reaction
• Substrate


  The substance that an enzyme acts on
• Enzymes usually only catalyse one specific reaction
• Enzyme action


  • Lock and key model
  • Induced fit model
• Changing the temperature


  Changes the rate of an enzyme-catalysed reaction
• Denaturation


  When the bonds holding the enzyme together break, changing the shape of the active site so the substrate won't fit anymore
• All enzymes have an optimum temperature and pH that they work best at
• Most human enzymes have an optimum temperature around normal body temperature
• Stomach enzymes work best at low pH, but enzymes in the small intestine like a higher pH
• Investigating the effect of pH on enzyme activity


  1. Add amylase and buffer solution to a boiling tube

  2. Add starch solution

  3. Take samples every 30 seconds and test with iodine

  4. Repeat with different pH buffers
• Rate of reaction


  A measure of how much something changes over time
• Enzymes used in digestion are produced by cells and released into the gut to mix with food
• Carbohydrases


  Enzymes that convert carbohydrates into simple sugars
• Carbohydrases


  • Amylase
• Proteases


  Enzymes that convert proteins into amino acids
• Proteases


  • Pepsin
  • Enzymes from the pancreas and small intestine
• Lipases


  Enzymes that convert lipids into glycerol and fatty acids
• Lipases


  • Enzymes from the pancreas and small intestine
• The body makes use of the products of digestion to make new carbohydrates, proteins and lipids
• Bile


  • Produced in the liver, stored in the gall bladder, released into the small intestine
  • Neutralises stomach acid and emulsifies fats
• The enzymes in the small intestine work best in alkaline conditions
• Digestion


  1. Salivary glands produce amylase

  2. Stomach produces hydrochloric acid and pepsin

  3. Pancreas produces proteases, amylase and lipase

  4. Small intestine produces proteases, amylase and lipase

  5. Liver produces bile
• The whole digestive system is a big hole that goes right through the body
• Food tests


  1. Prepare food sample

  2. Use Benedict's test to test for reducing sugars
• aria


  Ground up food
• Transferring the ground up food to a beaker and adding distilled water


  1. Transfer the ground up food to a beaker

  2. Add some distilled water