Anaerobic Respiration by Alcohol Fermentation

Glycolysis (Occurs in Cytoplasm): Glycolysis (Occurs in Cytoplasm):
Glucose (6C) has two phosphate groups added
to it by the hydrolysis of 2 ATP molecules:
ATP  ADP + P
This forms hexose bisphosphate (6C).
Hexose bisphosphate splits into two molecules
of triose phosphate (3C).
2H are removed from each molecule of triose
phosphate by a dehydrogenase enzyme.
An NAD molecule is converted to a reduced
NAD molecule:
NAD + H  Reduced NAD
The phosphate groups are removed & 2 ATP
molecules are generated from ADP & P:
ADP + P  ATP
This is substrate level phosphorylation of triose
phosphate (3C) to form pyruvate (3C).
The net products of glycolysis are:
2 Pyruvate molecules (3C).
2 Reduced NAD.
2 ATP.


Alcohol Fermentation: Alcohol Fermentation:
Pyruvate (3C) is decarboxylated by pyruvate
decarboxylase to form ethanal (2C) & release
CO2.
Ethanal (2C) accepts 2H from reduced NAD
(produced during glycolysis).
This is catalysed by ethanol dehydrogenase.
The NAD returns to be used in glycolysis.
This produces Ethanol.
Yeast can survive without oxygen, however it
will die when ethanol concentration reaches
15%.