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UNIT 6: RESPIRATION

UNIT 6: RESPIRATION. CELLULAR RESPIRATION COENZYMES USED DURING RESPIRATION PHASES OF RESPIRATION 4. FERMENTATION. CELLULAR RESPIRATION. The process by which cells ACQUIRE energy by BREAKING DOWN nutrient molecules produced by photosynthesis.

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UNIT 6: RESPIRATION

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  1. UNIT 6: RESPIRATION CELLULAR RESPIRATION COENZYMES USED DURING RESPIRATION PHASES OF RESPIRATION 4. FERMENTATION

  2. CELLULAR RESPIRATION • The process by which cells ACQUIRE energy by BREAKING DOWN nutrient molecules produced by photosynthesis. • It requires oxygen and gives off carbon dioxide. • It involves the complete breakdown of GLUCOSE to CO2 AND H2O. • C6H12O6 + 6O2 6CO2 + 6H20 + ENERGY

  3. C6H12O6 + 6O2 6CO2 + 6H20 + ENERGY • This equation points out that cellular respiration is an oxidation-reduction reaction. • OXIDATION is the LOSS of electrons. • REDUCTION is the GAIN of electrons. • GLUCOSE has been OXIDIZED and OXYGEN has been REDUCED

  4. C6H12O6 + 6O2 6CO2 + 6H20 + ENERGY • Glucose is a high-energy molecule, and its breakdown products, CO2 + H20, are low-energy molecules. • Thus energy is released. • This energy will be used to produce ATP molecules. • The cell carries out cellular respiration in order to build up ATP molecules.

  5. The pathway of CELLULAR RESPIRATION allow the ENERGY within a GLUCOSE MOLECULE to be RELEASED slowly so that ATP can be PRODUCED gradually. • The step-by-step breakdown of glucose to CO2 and H20 produce 36 to 38 ATP molecules.

  6. COENZYMES USED DURING RESPIRATION • Cellular respiration involves many individual metabolic reactions. • NAD+ • Coenzyme of oxidation-reduction (Redox coenzyme), • It accepts 2 electrons (e-) (oxidation) + a Hydrogen ion (H+ ) and produce NADH, • NAD+ + 2e- + H+  NADH • NADH give 2e- (reduction) + H+ ion  NAD+

  7. FAD • Another Coenzyme of oxidation-reduction (Redox coenzyme), • Sometimes used instead of NAD+ • It accepts 2 electrons (e-) (oxidation) + 2 Hydrogen ions (H+ ) and produce FADH2,

  8. PHASES OF RESPIRATION • Cellular respiration involves 3 phases: • Glycolysis • Kreb cycle / Citric acid cycle • Hydrogen transfer system / Oxidative phosphorylation

  9. GLYCOLYSIS • Takes place outside the MITHOCHONDRION in CYTOPLASM. • Does not require OXYGEN (ANAEROBIC) • Glycolysis is the breakdown of glucose to 2 molecules of PYRUVATE molecules with the release of H+ ions. • H+ ions are accepted by NAD+ and FAD to form NADH and FADH2 • Thus, NAD+ and FAD are REDUCED (gain e-)

  10. 2 ATP are used to start the process of glycolysis and 4 ATP’s are formed • Thus nett gain of 2 ATP molecules after glycolysis. • Diagrammatic representation of glycolysis: • See Page 40 of learning guide.

  11. KREB CYCLE / CITRIC ACID CYCLE • Takes place inside the MITHOCHONDRION in STROMA • Requires oxygen (AEROBIC) • Preperation of citric acid cycle: • PYRUVATE (3C) releases CO2 and 2 H+ ions • Forming a 2-C molecule (Acetyl group) which is carried by a co-enzyme (CoA) into the citric acid cycle in the form of Acetyl-CoA (2-C);

  12. 2-C Acetyl-CoA binds with a 4-C compound to form a 6-C compound, • The 6-C compound releases CO2 and 2 hydrogen ions to form a 5-C compound, • The CO2 is released into the atmosphere through the stomata of the leaf, • The H-ions are accepted by NAD+ to form NADH

  13. The 5-C compound releases CO2 and 2 hydrogen ions to form a 4-C compound, • The CO2 is released into the atmosphere through the stomata of the leaf, • The H-ions are accepted by NAD+ to form NADH • The 4-C compound loses another 4 H ions (accepted by NAD+ to form NADH) and then the cycle starts again. • A total of 20 H ions are released during the first 2 phases.

  14. Diagrammatic representation of citric acid cycle • See page 41 of learning guide.

  15. OXIDATIVE PHOSPHORYLATION / HYDROGEN TRANSFER SYSTEM

  16. Takes place in the MEMBRANE OF THE CRISTAE (mitochondrion) • Requires oxygen (AEROBIC) • Electrons are being transferred from 1 electron acceptor (NAD+/ FAD) to another, • With each transfer energy is released and used to form ATP (ADP + P) • Each time hydrogen is transferred the energy decreases

  17. The last hydrogen (electron) acceptor is OXYGEN which forms WATER, • Each transfer of H ions represents an OXIDATION reaction (loss of e-) which release a little energy • Total of 36 to 38 ATP is produced, which can be used to drive any metabolic reaction in an organism

  18. Diagrammatic representation of ETC • See Page 42 of learning guide.

  19. FERMENTATION • Fermentation is an anaerobic process • Does not require Oxygen to take place • 2 types of fermentation: • 1. Alcoholic fermentation • 2. Lactic acid fermentation

  20. ASSIGNMENT p 42 • Work in groups of 4 • Each group prepare ORAL PRESENTATION & WRITTEN PRESENTATION on FERMENTATION • Must include: • Cover page & index • Explain the concept of fermentation • Types of fermentation • Uses of fermentation for humans • Design practical investigation to demonstrate fermentation • Bibliography

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