Respiration A2

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  • Created by: Gemma
  • Created on: 19-09-13 20:42
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  • Respiration
    • The role of ATP
      • phosphorylated nucleotide
      • consists of adenosine + 3 phosphate groups
      • can be hydrolysed to ADP and Pi
        • This released 30.6KJ energy per mol
      • Universal energy currency
      • probably use 25-50 ATP per day
      • the hydrolysis of ATP is coupled with a synthesis reaction (DNA replication or protein synthesis), in cells.
      • The energy released from hydrolysis is an immediate source of energy for these biological processes.
    • Stages of respiration
      • Glycolysis
        • happens in the cytoplasm
          • Doesn't need oxygen so takes place in aerobic and anaerobic respiration
            • glucose (a 6-carbon sugar) is broken down into two molecules of pyruvate (a 3-carbon compound)
      • Link reaction
        • happens in the matrix of mitochondria
          • Pyruvate is decarboxylated and dehydrogenated
            • Only takes place under aerobic conditions, pyruvate is converted to either ethanol or lactate
              • Acetate is decarboxylated and dehydrogenated
              • Where ADP is phosphorylated to ATP
      • Krebs cycle
        • happens in the matrix of mitochondria
          • Acetate is decarboxylated and dehydrogenated
      • Oxidative Phosphorylation
        • happens in the folded inner membrane (cristae) of mitochondria
          • Where ADP is phosphorylated to ATP
    • Coenzymes
      • Help enzymes to carry out the oxidation reactions. Hydrogen atoms are combined with coenzymes such as NAD
      • NAD
        • organic, non-protein molecule
        • helps dehydrogenase enzymes to carry out oxidation reactions
        • Nicotinamide adenine dinucleotide
        • made of 2 linked nucleotides. One contains the adenine base, one contains the nicotinamide ring that accepts hydrogen atoms
        • When NAD has accepted 2 hydrogen atoms with their electrons, it is reduced. When it loses them, it is oxidised.
        • NAD operates during glycolysis, the link reaction, krebs cycle and during anaerobic ethanol and lactate pathways.
      • Coenzyme A (CoA)
        • Made from panthothentic acid, adenosine, 3 phosphate groups and cysteine.
        • It carries ethanoate (acetate) groups, made from pyruvate during the link reaction, onto krebs cycle.
        • Can also carry acetate groups that have been made from fatty acids or from  some amino acids onto krebs cycle


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