Respiration Anaerobic Respiration Triose phosphate Hexose 1 6

Respiration Anaerobic Respiration

Triose phosphate Hexose 1 -6 bisphosphate

Learning outcomes By the end of this lesson • Consolidate knowledge from KS 4 on anaerobic respiration • How energy is released by respiration in the absence of oxygen • How ethanol is produced in aerobic respiration • How lactate is produced in anaerobic respiration Success criteria • Explain why anaerobic respiration produces a much lower yield of ATP than anaerobic (Grade D - E) • Explain how ethanol and lactate are produced in respiration (Grade C) • Justify the importance of anaerobic respiration (Grade A – B)

Link from previous lesson • How much ATP is generated during each stage of respiration? Glycolysis Link reaction Krebs cycle Electron Transport Chain • Only glycolysis occurs in anaerobic conditions

Energy yields from aerobic and anaerobic respiration • Glycolysis 2 ATP • Link reaction • Krebs cycle 2 ATP • Electron transfer chain 26 ATP

Anaerobic respiration Why is oxygen important? Oxygen is important so the H atoms produced in glycolysis and krebs cycle can be converted to water and drive the production of ATP. What happens in the absence of oxygen? Krebs cycle and electron transport chain can’t take place and pyruvate builds up in the cell Anaerobic process of glycolysis is the only source of ATP So what happens to the pyruvate?

Anaerobic respiration in animals • Student 1 – Using the resources provided research anaerobic respiration in animals. Explain to your partner how pyruvate (C 3 H 4 O 3 ) is converted to lactate (C 3 H 6 O 3 ) • Student 2 – Using the resources provided research anaerobic respiration in plants and some microorganisms. Explain to your partner how pyruvate (C 3 H 4 O 3 ) is converted to ethanol (C 2 H 6 O) and another product. This is known as Explain how ethanol and lactate are Fermentation. produced in respiration (Grade C) • Include the word equations

The fate of pyruvate 8 of 39 © Boardworks Ltd 2009

Production of lactate in animals • Human cells do this by converting pyruvate to lactate. This reaction uses reduced NAD by oxidising it to NAD once more. • NAD is now available again to accept hydrogen so glycolysis continues. • If NAD is not regenerated, even glycolysis would have to stop, because there would be no oxidised NAD available to accept the hydrogen. • Write down the word equation to show lactate is made in anaerobic respiration. • Pyruvate + reduced NAD Lactate + NAD

Production of ethanol in plants and some microorganisms • Pyruvate loses a molecule of carbon dioxide and accepts hydrogen from reduced NAD to produce ethanol. • Write down the word equation for this proces • Pyruvate + reduced NAD ethanol + Carbon dioxide + NAD

Recipe for Success 1)What is anaerobic respiration? (Grade E) 2) What is produced by anaerobic respiration in animals? (Grade D) 3) What is produced by anaerobic respiration in yeast? (Grade D) 4) Which cells have more mitochondria, those that metabolize aerobically or anaerobically? (Grade C) 5) What molecule is important for glycolysis to continue? (Grade A-B)

Removing Lactate Why does oxygen uptake remain higher than normal following exercise? Lactate is oxidised back to pyruvate

Why is anaerobic respiration important? • Using the keywords below write down what happens in anaerobic respiration (in animals) and why it is important. pyruvate oxygen debt oxygen glycolysis muscles NAD Glycogen cramp fatigue Reduced NAD lactate • Peer assess explanations • Extension – Compare anaerobic and aerobic respiration Justify the importance of anaerobic respiration (Grade A – B)

What happens in anaerobic respiration and why it is important. • Anaerobic respiration occurs mostly in the muscles when oxygen is being used up quicker than it can be supplied, so an oxygen debt occurs. In the absence of oxygen glycolysis would usually stop as there would be a build up of reduced NAD. For glycolysis to continue, reduced NAD must be converted into NAD. This happens when pyruvate takes up 2 hydrogen atoms from reduced NAD to make lactate. Lactate builds up, increases H+ conc (p. H), enzymes inhibited. Lactate can be oxidised back to pyruvate (recycled) • Peer assess Justify the importance of anaerobic respiration (Grade A – B)

Task • Complete exam questions • SA using mark scheme provided

Plenary – True and False • More ATP is produced during anaerobic F respiration T • Anaerobic respiration in yeast has been exploited by humans for the brewing industry. • The krebs cycle and electron transport chain can not occur without oxygen T F • NAD is an important product of glycolysis • The replenishment of NAD for use in glycolysis is achieved by pyruvate accepting hydrogen from reduced NAD T

Learning outcomes By the end of this lesson • Consolidate knowledge from KS 4 on anaerobic respiration • How energy is released by respiration in the absence of oxygen • How ethanol is produced in aerobic respiration • How lactate is produced in anaerobic respiration Success criteria • Know that ethanol and lactate are produced in anaerobic respiration (Grade D - E) • Explain how ethanol and lactate are produced in respiration (Grade C) • Justify why anaerobic respiration produces less ATP than aerobic respiration (Grade A – B)

Anaerobic Respiration in animals

Anaerobic Respiration in microorganisms and plants