anaerobic respiration in mammals and yeast Flashcards
What is anaerobic respiration
The release of energy from substrates such as glucose in the absence of oxygen
What happens if there is no oxygen
Electron transport chain can’t function so Krebs cycle and the link reaction also stops
What a happens if the Krebs cycle and link reaction stop too
Only source of ATP is the anaerobic process of glycolysis
What has to happen if you want the process to carry on if Krebs cycle and link reaction stop
The reduced nad from oxidation of glucose has to be reiniciar so that glycolysis can keep operating
Advantages if residing reduced nad to keep glycolysis operating
Increases chances of the organism surviving under temporary adverse conditions
What are the 2 pathways ti repitiese nad I’m eukaryotic cells
Fungi such as yeast Use ethanol (alcohol) fermentation
Animals use lactate fermentation
Do the pathways produce ATP
No
So where is ATP made from
By substrate level phosphorylation during glycolysis
What does glycolysis produce
2 molecules of ATP
2 molecules if reduced nad
2 molecules of pyruvate
Per molecule of glucose
Where does lactate fermentation occur
Mammalian muscle tissue during vigorous activity e.g. running to escape a predator when demand for ATP for muscle contraction is high and there is an oxygen deficit
Process of lactate fermentation
Reduced nad must be re oxidised to nad+
Pyruvate is the hydrogen acceptor
Accepts hydrogen atoms from reduced nad
Nad is now re oxidised and is available to accept more hydrogen atoms from glucose
Glycolysis can continue
Generates enough atp to sustain muscle contraction
Lactate dehydrogenase catalysed the oxidation of reduced nad
Together with the reduction of pyruvate to lactate
Extra to lactate fermentation
Lactate os then carried in the blood from muscles to the liver
What happens to lactate when more oxygen is available
Converted back to pyruvate which may enter Krebs cycle through link reaction or converted to glycogen or glucose
What causes muscle fatigue
The reduction in oh that will reduce enzyme activity in the muscles not the build up of lactate
Steps of alcoholic fermentation
Under anaerobic conditions in yeast cells
Each pyruvate molecule loses a carbon dioxide molecule, it is decarboxylated and becomes ethanal
This reactions I’d catalysed by pyruvate decarboxylase which isn’t present in animals and has a coenzyme bound to it
Ethanol a accepts hydrogen atoms from reduced nad which becomes reoxidised as ethanal is reduced to ethanol (catalyst by ethanol dehydrogenase)
The reoxidised nad can now accept more hydrogen atoms from glucose during glycolysis
