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Respiration

Respiration. Link Reaction and Krebs Cycle. Glycolysis recap. Where does it happen? Why is it required? What does it produce? Anaerobic versus Aerobic. Link Reaction. Pyruvate needs to be OXIDISED before it enters the Krebs Cycle What is a good oxidising agent?. Link Reaction.

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Respiration

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  1. Respiration Link Reaction and Krebs Cycle

  2. Glycolysis recap • Where does it happen? • Why is it required? • What does it produce? • Anaerobic versus Aerobic

  3. Link Reaction • Pyruvate needs to be OXIDISED before it enters the Krebs Cycle • What is a good oxidising agent?

  4. Link Reaction • Pyruvate needs to be OXIDISED before it enters the Krebs Cycle • What is a good oxidising agent? • Nicotinamide adenine dinucleotide

  5. Link Reaction

  6. Link Reaction

  7. Investigation Bio 6T/Q11 • access to a yeast culture in a large flask and to a yeast culture in a small flask ● 250 cm3 sterile beaker ● sterile measuring cylinder ● sterile water ● sterile glass rods ● sterile graduated pipettes or syringes ● spreader in sterilising solution ● 2 sterile agar plates ● marker pen ● acetate grid ● sticky tape and scissors

  8. Investigation Bio 6T/Q11 • Aim: • Variables: • Null Hypothesis: • Which test will you choose? • How many samples will you choose and how will you choose them?

  9. Session 1 1. Shake the sample of yeast culture from the small conical flask. 2. Take 1 cm3 of the yeast culture and add it to a 250 cm3 beaker. 3. Add 200 cm3 of sterile water to the beaker. 4. Stir the mixture and immediately remove 0.1 cm3 of the diluted yeast culture from the beaker using a 1 cm3 graduated pipette or syringe. 5. Lift the lid of an agar plate carefully so you can just put the tip of the graduated pipette or syringe through the small gap. 6. Put the 0.1 cm3 of the diluted yeast culture onto the agar keeping the lid as near the plate as possible. 7. Shake the spreader to remove excess sterilising solution if necessary. Use the sterile end of the spreader to spread the yeast culture evenly over the agar. 8. Close the lid. Label the plate clearly at the edge to show the size of the conical flask from which the yeast culture was taken. 9. Repeat steps 1 to 8 with the large flask. 10. Put small pieces of sticky tape on the edges of the plates to hold the lids on. 11. Incubate the plates for 24 hours.

  10. 12. Turn one agar plate upside down so that its base faces upwards. 13. Place the acetate grid on the base of the agar plate. 14. Select 15 separate 10 mm squares at random. Count the number of yeast colonies in each of the 15 squares. 15. Repeat steps 12 to 14 with the second agar plate.

  11. Results • Statistical test • Graph

  12. Test Statistic

  13. Link Reaction and Krebs Cycle

  14. KREBS CYCLE

  15. Coenzyme A 2H NADH2 carbon dioxide recycled The pyruvic acid (pyruvate) molecules formed during glycolysis diffuseinto the fluid matrix of the mitochondrion Each three carbon pyruvic acid molecule is converted into a two carbon compound called Acetyl CoA The two carbon acetyl group is needed to drive KrebsCycle Pyruvic acid is oxidised to Acetyl CoA through the removal of a pair ofhydrogen atoms The hydrogen atoms are accepted by the hydrogen carrier NAD The Coenzyme A group is recycled CO2is removed from pyruvic acid to reduce the number of carbon atoms to two – this process is called decarboxylation The Link Reaction yields: A 2-carbon acetyl group needed to drive Krebs Cycle; The reduced hydrogen carrier NADH2; a molecule of CO2

  16. CO2 CO2 4C Oxaloacetic acid 6C Citric Acid NADH2 2H 2H NADH2 NADH2 2H 5C Keto Glutaric acid 4C Malic Acid 2H FADH2 4C Succinic Acid The 6C Citric Acid is oxidised to the 5C Keto Acid The 2C acetyl group of Acetyl CoA combines with the 4C acid, Oxaloacetic Acid, to form the 6C Acid, Citric Acid Oxidation involves the removal of a pair of hydrogen atoms that are accepted by the hydrogen carrier NAD to form NADH2 Coenzyme A is recycled The number of carbon atoms is reduced by the removal of carbon dioxide - decarboxylation NAD accepts the pair of hydrogen atoms from this oxidation The 5C acid is oxidised to the 4C succinic acid generating another NADH2 and CO2 molecule The 4C malic acid is finally oxidised back to the 4C oxaloacetic acid enabling the cycle to operate again The 4C succinic acid is oxidised to the 4C malic acid This step also generates sufficient energy to form a molecule of ATP In this case the hydrogen carrier is FAD

  17. RESPIRATION

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