Biology - Digestion

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  • Digestion
    • A tissue is a group of cells with similar structures and functions
    • Organs are collections of tissues preforming specific functions
      • Organs are organised into organ systems , which work together to form organisations
        • Organ Systems are groups of organs that preform specific functions in the body
    • The digestive system in a mammal is an organ system where several organs work together to digest and absorb food
    • Carbohydrates are made up of units of sugar
      • Simple Sugars are carbohydrate that contain only one or two sugar units- they turn the blue bendecits solution brick red when heated
      • Complex Carbohydrate contains long chain of similar sugar units bonded together , starch turns yellow red in iodine solution (blue-black)
      • Carbohydrate such as amylase catalyse the breakdown of carbohydrate in to simple sugars
    • Lipids consists of 3 molecules of fatty acids bonded to a molecule of glycerol. The ethanol test indicates the presence of lipids in solutions
      • Lipase catalyse the breakdown of lipids to fatty acids and glycerol
    • Protein molecules are made up of long chains of amino acids. Biueret reagants turns from blue to purple in the presence of proteins
      • Protease catalyse the breakdown of proteins to amino acids
      • The protease enzymes of the stomach work best in acid conditions. The stomach produces hydrocloric acids , which maintains a low pH
    • Catalysts increase the rate of chemical reactions without changing chemically themselves
    • Enzymes are biological catalysts and catalyse specific reactions in living organisations due to the shape of their active site. This is the lock and key theory of enzyme action
      • Enzymes are proteins. The amino acid chains are folded to form the active site , which makes the shape of a specific substrate molecule
    • The substrate bind to the active site and the reaction is catalysed by the enzyme
    • Metabolism is the sum of all the reactions of a cell or the body
    • Enzyme activity is affected by temperature and pH
    • High temperatures denatures the enzyme changing the shape of the active site
    • pH can affect the shape of the active site of an enzyme and make it work very efficiently or stop it working
    • Digestion involves the breakdown of large insoluble molecules into a soluble substance that can be absorbed into the blood across the wall of the small intestine
    • The enzymes made in the pancreas and the small intestine work the best in alkaline conditions
      • Bile produced by the liver , stored in the gall bladder , and released through the bile duct neutralises acids and emulisifies fat

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