A Level Biology - Respiration

A Level Biology - Respiration
Covers:
Important definitions,
Aerobic respiration,
Anaerobic respiration,
Exercise,
Other respiratory pathways.

Transcript

1. Respiration
2. Important definitions • Anabolic reactions – small molecules are built up into bigger molecules • Catabolic reactions – large molecules are broken down into smaller molecules • Chemiosmosis – energy released from the electron transport chain that pumps H+ ions into the mitochondrial intermembrane space • Decarboxylation – removal of a CO2 molecule • Dehydrogenation – removal of a H+ molecule • Hydrolysis – to split apart using water • Metabolic pathway – a series of small, enzyme controlled reactions • Oxidoreductases – enzymes that catalyse oxidation and reduction reactions • Phosphorylation – the addition of a phosphate molecule • Redox reactions – series of oxidation and reduction reactions
3. Aerobic respiration (producing energy with oxygen)
4. Glycolysis occurs in cytoplasm Glucose (6C) Hexose phosphate (6C) Hexose bisphosphate (6C) 2x Triose phosphate (3C) Intermediates 2x Pyruvate molecules (3C) 2x ATP 2x ATP ATP ATP 2x H+ Phosphorylation Oxidation 2x NAD 2x NADH
5. The Link reaction occurs in mitochondrial matrix and runs twice for every molecule of glucose 2x Pyruvate molecules (3C) Acetyl CoA (2C) 2x NAD 2x NADH CO2 Coenzyme A
6. The Krebs cycle occurs in mitochondrial matrix and runs twice for every molecule of glucose Acetyl CoA (2C) Citric acid (6C) Oxaloacetate (4C) 5 carbon compound (5C) CO2 CO2 ATP 2x NAD 2x NADH FAD FADH2
7. Oxidative phosphorylation 1. NADH and FADH2 in mitochondrial matrix dissociate from the hydrogen (H+ protons and e- electrons). The NAD+ and FAD+ go back and accept more hydrogen in glycolysis, link reaction and Krebs cycle 2. High energy electrons are passed along an electron transport chain (in the inner mitochondrial membrane) and down an energy gradient 3. Energy released by these electrons is used to actively pump H+ from the matrix into the intermembrane space using protein pumps 4. H+ diffuses back into the matrix (down an electrochemical gradient) through a stalked particle which is also the enzyme ATP synthase. This is chemiosmosis 5. Diffusion of H+ down an electrochemical gradient releases energy which is used to synthesise ATP 6. O2 is used as the final electron accepter at the end of the electron transport chain 7. The now negatively charged oxygen binds to H+ in the matrix and forms water
8. 1 2 3 4 5 6 7
9. Anaerobic respiration (producing energy without oxygen)
10. Exercise • If particularly long or hard, muscles cannot get enough oxygen to supply their needs • The products of glycolysis do not progress to the link reaction or the Krebs cycle • Hydrogens do not go to the electron transport chain but are donated to pyruvate • Pyruvate becomes (toxic) lactic acid/lactate which moves out of cells into the blood system • When exercise stops high levels of lactate still remain in the blood stream • Lactate must be oxidised back to pyruvate so it can progress to the link reaction and Krebs cycle • Oxygen is required to oxidise the pyruvate • Breathing heavily often occurs after exercise to collect oxygen to repay the body’s “oxygen debt”
11. Sprint runners May run 95% of a race relying on the anaerobic respiration of their muscles • Maintain a much higher level of aerobic respiration • Muscles could not continue to work for the length of time needed if lactate levels are not kept to a minimum • Training develops a better oxygen/blood supply and a higher toleration to lactate levels Long distance runners
12. Mammalian muscle cells Glucose Pyruvate Lactic acid 2x ATP 4x ATP 2x NADH 2x NAD 2x NADH Glycolysis
13. Yeast, other microbes and plants in water logged soil Glucose Pyruvate Ethanal Ethanol 2x ATP 4x ATP 2x NADH CO2 2x NADH 2x NAD Glycolysis
14. Other respiratory pathways
15. Proteins Triglycerides Glucose Triose phosphate Pyruvate Acetyl CoA Krebs cycle Glycerol Fatty acids 2C compounds Anaerobic respiration Lactate Oxygen debt Amino acids NH3 Deamination in liver Urea excreted by kidneys Hydrocarbon (keto group)