12.4 Anaerobic respiration Flashcards
What processes can’t happen if oxygen isn’t present and why
Neither the Krebs cycle or electron transfer chain can occur
This is because all the NAD and FAD will be reduced to NADH and FADH.
This means there is none left to pick up the H+ ions produced in krebs cycle so the enzymes stop working
Why is oxygen needed in respiration
It is the terminal electron acceptor, so if the hydrogen ions produced in glycolysis/krebs cycle, are to be used in production of ATP.
Does glycolysis need oxygen
No it is an anaerobic process
However, for the process of glycolysis to continue, its products of pyruvate and hydrogen must be constantly removed
Eg hydrogen must be released from NADH to regenerate NAD.
So without this, almost all the NAD will be reduced so there is none to take up the hydrogen produced by glycolysis.
So glycolysis will eventually grind to a halt
How is NAD replenished
Pyruvate molecule from glycolysis accepts the hydrogen from reduced NAD
So this oxidised NAD can now be used in further glycolysis
What is produced in anaerobic respiration of plants/yeast
What is this used for in industry
Pyruvate is converted to ethanol and carbon dioxide
C6H12O6–> C2H5OH + CO2
Yeast is used in industry to ferment carbohydrates in plants so eg grapes to wine
What is produced in anaerobic respiration of animals
Lactate is produced
What happens in anaerobic respiration in plants
What is the equation
The pyruvate molecule produced at the end of glycolysis loses a molecule of CO2 and accepts a hydrogen from NADH to make ethanol
pyruvate + NADH —> Ethanol + CO2 + NAD
Why is lactate production in animals useful
. It means we can survive a temporary shortage of oxygen
This is useful when mammals give birth, so the baby mammal can survive in that short period
Or also in an animal living in water where oxygen production is low
When does lactate production occur in animals
It usually occurs in muscles as a result of strenuous exercise
Where oxygen is being used up faster than it is being supplied so therefore an oxygen debt occurs
However it is important that the muscles can still function despite the shortage of oxygen, eg when prey is fleeing from a predator
What is the equation for anaerobic respiration in animals
Pyruvate + NADH —> Lactate + NAD
Each pyruvate molecule takes up two hydrogen atoms from NADH produced in glycolysis to form lactate
What two ways is energy from respiration derived
. Substrate level phosphorylation in glycolysis and krebs cycle
This is where a phosphate is directly transferred from a respiratory intermediate to ADP to make ATP
. Oxidative phosphorylation is in the electron transfer chain.
So indirect linking of energy from phosphate to ADP to make ATP.
It involves energy from hydrogen atoms that are carried on NAD and FAD
