4. Respiration


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4. Respiration

  1. 1. Chemistry of Respiration Unit 1 - Cell Biology SQA HIGHER BIOLOGY
  2. 2. Topic Content <ul><li>Glycolysis. </li></ul><ul><ul><li>The breakdown of glucose (6C) to pyruvic acid (3C) with a net production of ATP. </li></ul></ul><ul><ul><li>Location of process within the cytoplasm. </li></ul></ul><ul><li>Krebs (Tricarboxylic acid, Citric acid) cycle. </li></ul><ul><ul><li>The production of carbon dioxide and hydrogen. </li></ul></ul><ul><li>The cytochrome system. </li></ul><ul><ul><li>The production of ATP and water. </li></ul></ul><ul><li>Mitochondrion structure. </li></ul><ul><li>Distinction between aerobic and anaerobic phases of respiration. </li></ul>
  3. 3. Introduction <ul><li>Make molecular models to demonstrate the overall chemical reaction of respiration. </li></ul><ul><li>The large ordered molecules of glucose store a lot more energy than the small disordered 6CO 2 and 6H 2 O molecules. </li></ul><ul><li>What activities, carried out by cells, require energy? </li></ul><ul><li>Why is there a stepwise breakdown of glucose to carbon dioxide and water? </li></ul>
  4. 4. Structures for models
  5. 5. Overview of Respiration <ul><li>What are the four stages of Respiration? </li></ul>GLYCOLYSIS LINK REACTION KREBS CYCLE CYTOCHROME SYSTEM <ul><li>Copy and annotate the diagram using the information from MSS 16-18. </li></ul><ul><li>Key points </li></ul><ul><ul><li>Location </li></ul></ul><ul><ul><li>Carbon atoms </li></ul></ul><ul><ul><li>Energy </li></ul></ul>
  6. 6. Mitochondrion Structure <ul><li>Can you recall the structures of the mitochondrion? </li></ul><ul><li>What happens where? </li></ul>
  7. 7. Glycolysis <ul><li>Glycolysis is the first main stage in respiration. </li></ul><ul><ul><li>Where does it occur? </li></ul></ul><ul><ul><li>What are the respiratory substrates which can be used for glycolysis? </li></ul></ul><ul><li>Glycolysis is the splitting (lysis) of glucose and does not involve oxygen. </li></ul><ul><li>Glycolysis is common to both aerobic and anaerobic respiration. </li></ul>
  8. 8. Glycolysis
  9. 9. Glycolysis <ul><li>Here are some important points: </li></ul><ul><li>In glycolysis, one molecule of glucose (6C) is broken down into 2 molecules of pyruvate (3C). </li></ul><ul><li>Each reaction is catalysed by different enzymes. </li></ul><ul><li>As sugars are not very reactive, 2 molecules of ATP are used to add 2 phosphates to the 6-carbon sugar to activate it. </li></ul><ul><li>Later on in glycolysis 4 molecules of ATP are synthesised from the energy released during the reactions. </li></ul><ul><li>There is a net gain of 2 molecules of ATP for every molecule of glucose broken down into pyruvate. </li></ul>
  10. 10. Glycolysis <ul><li>Glycolysis is an oxidation reaction: removal of electrons and hydrogens reduce 2NAD to 2NADH 2 . </li></ul><ul><li>NAD is a coenzyme which helps dehydrogenase enzymes to catalyse redox reactions. </li></ul><ul><li>What happens to the NADH 2 ? </li></ul>
  11. 11. Link Reaction <ul><li>Pyruvic acid diffuses into the matrix of the mitochondrion. </li></ul><ul><li>It is converted into a 2-carbon compound called acetyl CoA. </li></ul><ul><li>This reaction releases hydrogen which is used to reduce NAD. </li></ul>
  12. 12. Link Reaction
  13. 13. Krebs Cycle <ul><li>The Krebs Cycle is also known as the Tricarboxylic Acid and the Citric Acid Cycle. </li></ul><ul><li>It is a series of reactions in which enzymes strip away electrons and H + ions from each acetyl group to reduce NAD. </li></ul><ul><li>Acetyl CoA reacts with a 4-carbon compound to form a 6-carbon compound (citric acid). </li></ul><ul><li>Citric acid is gradually converted, in a cyclic series of reactions, back to the 4-carbon compound, the carbons being lost as carbon dioxide. </li></ul>
  14. 14. Krebs Cycle
  15. 15. The Cytochrome System
  16. 16. The Cytochrome System <ul><li>Hydrogens which have been removed are passed through a series of carriers and finally are received by oxygen to form water. </li></ul><ul><li>If this oxygen is not present to act as the final acceptor, the hydrogen cannot pass through the system and complete oxidation cannot take place. </li></ul><ul><li>This system of hydrogen carriers is the most important means of releasing energy in respiration. </li></ul><ul><li>Energy may be released from a few individual steps in the overall process, but that most of the energy is made available by the cytochrome system. </li></ul>
  17. 17. ATP Output <ul><li>For every glucose respired, there is approximately 38 ATP molecules produced. </li></ul>