2. glycolysis

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  1. 1. Respiration overview
  2. 2. Respiration requires organic molecules to be used as fuel The starting molecule is usually glucose It is broken down in a series of steps This will give potential chemical energy
  3. 3. In the first step glucose is split This stage is called glycolysis In a series of enzyme controlled reactions two molecules of pyruvate are made
  4. 4. Pyruvate can stay in the cytoplasm and enter into the anaerobic pathway This occurs in the absence of oxygen
  5. 5. If oxygen is present pyruvate enters the mitochondrion It is converted to Acetyl CoA in the Link reaction
  6. 6. This molecule now enters the Krebs Cycle where NAD and FAD are reduced Most of the CO2 is made at this stage
  7. 7. The reduced molecules carry Hydrogen to the Electron transfer Chain This generates ATP The final hydrogen acceptor is oxygen
  8. 8. Hydrogen Carrier Molecules There are two of these in respiration NAD Nicotinamide Adenine Dinucleotide This is a co-enzyme This can accept electrons and hydrogen and become reduced FAD Flavin adenine dinucleotide It is derived from Vitamin B2 (riboflavin)
  9. 9. NAD NADreduced NAD is a hydrogen carrier molecule When it picks up hydrogen it becomes reduced
  10. 10. FAD is more complex all you need to know is it will carry hydrogen to the final stage of respiration
  11. 11. Glycolysis
  12. 12. This is the splitting of sugar or more specifically glucose It takes place in the cytoplasm 6 Carbon glucose is split into 3 Carbon Pyruvate in a series of steps ATP is used in the first steps but generated in the last few steps NAD is reduced
  13. 13. In the first steps of glycolysis glucose has 2 phosphates attached We say glucose is phosphorylated These are transferred from ATP So two ATP molecules are used A hexose biphosphate is made We will tally the NAD reduced made here We will keep tally of ATP here
  14. 14. This hexose phosphate is split into TWO triose (3C) phosphates So from her onwards everything must be X2 for each molecule of glucose
  15. 15. The 3 Carbon phosphates look like this in case you are interested
  16. 16. Each triose phosphate then have a hydrogen removed This is attached to NAD which becomes NADreduced This is an energy yielding step ADP is phosphorylated to ATP
  17. 17. Another phosphate is lost to form Pyruvate and another ATP
  18. 18. Pyruvate looks like this It is an acid
  19. 19. So the products of glycolysis of one molecule of glucose are: 2 x pyruvate 2 x NADreduced 2 x ATP (net)