36. REDOX REACTIONS

Question 1

1. Why do Catabolic Pathways yield energy?

Answer 1

• they transfer electrons (energy)

Question 2

2. What are Redox reactions?

Answer 2

• they are reactions that involve the transfer of electrons
• these electrons are transferred from one reactant to
  another
• this is done by oxidation and reduction

Question 3

3. What is Oxidation?

Answer 3

• it is when a substance loses electrons
• the substance is oxidised

Question 4

4. What is Reduction?

Answer 4

• it is when a substance gains electrons
• the substance is reduced

Question 5

5. What is Oxidised and what is Reduced during Cellular Respiration?

Answer 5

• glucose is oxidised
• glucose is known as the fuel
• oxygen is reduced

Question 6

6. Classify the three stages of Cellular Respiration as either Aerobic or Anaerobic?

Answer 6

1. Glycolysis = Anaerobic
2. Krebs Cycle (Citric Acid Cycle) = Aerobic
3. Oxidative Phosphorylation = Aerobic

Question 7

7. What happen during Glycolysis?

Answer 7

• glucose breaks down into 2 molecules of Pyruvate

Question 8

8. What happens during the Krebs Cycle (Citric Acid Cycle)?

Answer 8

• the Pyruvate is broken down into CO₂

Question 9

9. What happens during Oxidative Phosphorylation?

Answer 9

• this stage is driven by the Electron Transport Chain
  (ETC)

ETC CAUSES CHEMIOSMOSIS:
- this generates ATP
- this is done by ATP synthase

MOST OF THE ATP (90%):
- is generated by this stage
- this is about 32 - 34 ATP molecules

Question 10

10. How much ATP does the Glycolysis and Krebs Cycle (Citric Acid Cycle) generate?

Answer 10

• 10%
• it does this through substrate level phosphorylation

Question 11

11. What carries the electrons to the Cytosol for the Glycolysis stage?

Answer 11

• Electrons

Question 12

12. What carries the electrons to the Mitochondria for the Krebs Cycle Process and the Oxidative Phosphorylation process?

Answer 12

• NADH
• FADH2

Question 13

13. What happens during Cellular Respiration?

Answer 13

• the energy from the organic compounds is produced
• it is produced in the form of electrons

Question 14

14. What transports the electrons (energy)?

Answer 14

• Redox Coenzymes
• NAD⁺
• FAD

Question 15

15. Where are the electrons released from?

Answer 15

• they are released from the oxidation of organic compounds

THIS IS DURING:
- Glycolysis
- Krebbs Cycle

Question 16

16. What happens to the electrons after they are released?

Answer 16

1. they are transferred to the co-enzymes:
   
   • NAD⁺
   • FAD
2. these co-enzymes are reduced to:
   
   • NADH
   • FADH₂
3. these reduced coenzymes are then transferred:
   
   • to the Electron Transport Chain (ETC)
   • this happens during the 3rd Stage of Respiration
4. these reduced coenzymes are transferred to Oxygen:
   
   • this is used in the production of water

Question 17

17. What does NAD stand for?

Answer 17

• Nicotinamide Adenine Dinucleotide

Question 18

18. What does FAD stand for?

Answer 18

• Flavin Adenine Dinucleotide

Question 19

19. What is FAD reduced into?

Answer 19

• FADH₂
• it has two hydrogens
• the electrons are transferred to the Electron
  Transport Chain
• these are long and big molecules

Question 20

20. What is FADH₂ oxidised into?

Answer 20

• FAD

Question 21

21. What is Dehydrogenases?

Answer 21

• the enzymes that remove electrons (e﹣)
• they remove these from organic compounds
• these compounds become oxidised
• THESE ELECTRONS ARE TRANSFERRED TO:
  
  • NAD⁺
  • FAD

Question 22

22. What is NAD⁺ reduced into?

Answer 22

• NADH
• it has only one hydrogen

Question 23

23. What is each electron (e﹣) transferred with?

Answer 23

• a proton
• H⁺
• these hydrogens are removed from organic substances

REACTION:
H → H⁺ + e﹣