1. Starter Define anaerobic respiration
The release of energy from substrates, such as glucose in the absence of oxygen

2. Anaerobic Respiration: Learning outcomes
Explain why anaerobic respiration produces a much lower yield of ATP than aerobic respiration;
Compare and contrast anaerobic respiration in mammals and in yeast;
Q. What is the final electron acceptor in oxidative phosphorylation?
A. Oxygen

3. No Oxygen? Electron transport chain can’t function
Glycolysis is the only process that can function as anaerobic!
The NAD that has been reduced (Hydrogen added) has to be re-oxidised (Hydrogen removed) so that it can keep accepting Hydrogen atoms in glycolysis
There are two ways that NAD can be reoxidised
Fungi e.g. yeast use ethanol fermentation
Animals use lactate fermentation
Neither of these produce ATP, but two ATP are made during glycolysis by substrate level phosphorylation
TASK GLYCOLYSIS: Draw what you know onto whiteboards

5. Alcohol Fermentation: Yeast cells in anaerobic conditions
Pyruvate
Ethanal
Ethanol
CO2
Pyruvate decarboxylated
Catalysed: Pyruvate decarboxylase
Ethanal accepts H atoms from reduced NAD.
Catalysed by Ethanol dehydrogenase 2H
NAD
Reduced NAD
ReoxidisedNAD can accept more H atoms

6. Yeast Yeast can live without oxygen
It is killed if it remains in the ethanol it has produced if the concentration builds up to 15%
Rate of growth is faster in aerobic conditions
In brewing, yeast is normally grown aerobically at first and then anaerobically

7. TASK: 5 minutes
Summarise anaerobic respiration in yeast: Alcoholic fermentation

8. Lactate Fermentation: mammalian tissue
Occurs in muscle tissue during vigorous activity
When demand for ATP is high and there is an oxygen deficit
Glycolysis can continue generating enough ATP to sustain muscle contraction for brief vigorous activity

9. SO GLYCOLYSIS CAN CONTINUE
Lactate Fermentation
Pyruvate
Lactate 2H
NAD
Reduced NAD
Catalysed by Lactate dehydrogenase
NAD is now reoxidised and can accept more H atoms from glucose
SO GLYCOLYSIS CAN CONTINUE
Pyruvate is the H acceptor (H atoms) from reduced NAD

10. Anaerobic Respiration
The working muscle cells can continue this type of anaerobic energy production at high rates for one to three minutes, during which time lactate can accumulate to high levels.
Lactate accumulates in the muscles (cause cramp) How???
Lactate forms lactic acid in solution: pH falls, inhibits enzymes, inhibits glycolysis!
QUICK INVESTIGATION: FEEL THE BURN!
Why would this happen? What is happening?
Defence mechanism for our bodies to prevent permanent damage during physical exertion. And pain gets us to stop too!

11. How... As lactate builds up pH falls Inhibits glycolysis because....
Hydrogen ions from lactic acid accumulate in cytoplasm,
They neutralise the –vely charged groups in the active site of enzyme
This affects the attraction between charged groups on the substrate+ active site

12. Getting rid of lactate:
Lactate (lactic acid) carried away in blood to the liver
When exercise is over lactate is oxidised back to pyruvate (this requires additional oxygen – referred to as the oxygen debt – where you breathe very deeply and rapidly).
Then It is oxidised to carbon dioxide + water via the Krebs cycle, releasing energy to synthesise ATP
In liver some lactate can be converted to glucose/ glycogen: stored in muscle/liver.
Lactate does not cause muscle fatigue: reduction in pH that reduces enzyme activity in the muscles
The whole point of anaerobic respiration is to reoxidise NAD (recycles) (remove Hydrogen) to that Glycolysis can continue

13. Extension… Three energy systems summary: Cells cannot store much ATP
At start of exercise immediate recharge of ATP is made using creatine phosphate
Stored in muscles and can be hydrolysed to release energy
Energy is used to regenerate ATP from ADP and Pi.
Creatine phosphate provides the Pi
Creatine phosphate creatine + Pi
ADP + Pi ATP
Creatine phosphate + ADP creatine + ATP
No oxygen needed
Provide energy for 6-10 seconds
Known as the ATP/PC system

14. Task: 10 minutes
Summarise lactate fermentation in mammals

15. Complete a comparison of anaerobic respiration in yeast and mammals
Hydrogen acceptor
Is carbon dioxide produced
Is ATP produced
Is NAD reoxidised
End products
Enzymes involved

16. Complete a comparison of anaerobic respiration in yeast and mammals
Hydrogen acceptor
Ethanol
Pyruvate
Is carbon dioxide produced
Yes No
Is ATP produced
Yes 2x in glycolysis
Is NAD reoxidised
End products
Ethanal and carbon dioxide
Lactate
Enzymes involved
Pyruvate decarboxylase/ ethanol dehydrogenase
Lactate dehydrogenase

17. Thinking???
Diving mammals, such as this Galapagos sea lion, evolved adaptations allowing them to stay underwater for prolonged periods of time
Suggest what they could be..

18. Sea lion What physical adaptations?
Lower metabolic rate: Diving mammals will slow their heart rate, stop their breathing, and shunt blood flow from their extremities to the brain, heart, and muscles when starting a dive
Diving mammals—including whales, seals and otters, have more haemoglobin/myoglobin (oxygen store) in their muscles.
Haemoglobin has a higher affinity for oxygen
Respiration: large supplies of NAD, so more glycolysis, less build up of lactate; more pH buffers

19. Examination questions! They like anaerobic respiration!!
Complete
Examination questions! They like anaerobic respiration!!
Organisms require energy..(4)
(b) In anaerobic conditions compound F.. (5)
(b) Yeast cells carry out anaerobic respiration (4)
(c) If oxygen is not present (5)
Respiration can be anaerobic or aerobic..(6)
Why does anaerobic respiration..(7)
31 marks…!!!