5. anaerobic respiration
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Transcript of 5. anaerobic respiration
Anaerobic Respiration
Anaerobic RespirationWill take place if there is no free oxygen
Because there will be no final hydrogen acceptor
So the ETC cannot take place
So there is no oxidative phosphorylation to form ATP
Glucose is converted to Pyruvate in glycolysis
NAD is reducedThere is a net production of 2 ATP
NAD must be recycled - There are two alternate pathways
Ethanol pathway Lactate pathway
Ethanol Pathway/ Alcoholic
Fermentation
This occurs in some plants (facultative anaerobes) and in yeast
It takes place in the cytoplasm
Glycolysis occurs in the cytoplasm
ATP is being made, even though it is in a small amount
NAD is reduced and must be recycled
Pyruvate will accumulate unless it is removed
Pyruvate is decarboxylated to ethanal
The CO2 given off here is what makes bread rise when dough is mixed with yeast
Ethanal is reduced to Ethanol using hydrogen from NADredThe enzyme required for this process is Alcohol dehydrogenaseNAD can now be reused and glycolysis can continue producing ATP
The fermentation process is used to make alcoholic beverages
The Lactate PathwayThis occurs in mammalian skeletal muscles during exertion
When pyruvate from glycolysis is produced faster than it can be oxidised in the Krebs cycle
This is because the supply of oxygen cannot meet the demand
Glycolysis occurs in the cytoplasm
ATP is being made, even though it is in a small amount
NAD is reduced and must be recycled
Pyruvate will accumulate unless it is removed
Pyruvate acts as the Hydrogen acceptorIt accepts hydrogen from NADred
Pyruvate is converted to lactate by lactate dehydrogenaseNAD available to be reduced again in glycolysis
Pyruvate does not accumulate
ATP is made in small amounts by glycolysis
The skeletal muscles can continue to work
Lactate is toxic and must be removedThis pathway can be reversed but needs oxygen
An oxygen debt therefore exists
Lactate is carried in the blood from the muscles to the liver
20% is oxidized to CO2 and H2O, 80% is converted to glycogen and stored