Summary: Anaerobic respiration
This occurs in the absence of oxygen.
In aerobic respiration, neither the Krebs cycle nor the electron transfer chain can take
place. The only ATP that can be produced is formed by glycolysis.
In eukaryotic cells, anaerobic respiration occurs in:
A. In plants, and in microorganisms such as(yeast) where the pyruvate is converted
to ethanol and carbon dioxide.
i. The pyruvate molecule formed at the end of glycolysis loses one molecule
of carbon dioxide and then gains hydrogen from reduced NAD to produce
ethanol.
ii. The summary equation is:
Pyruvate + reduced NAD ethanol + carbon dioxide + oxidised NAD
iii. Used in the brewing industry, and ethanol is the important product.
iv. Yeast is grown in these anaerobic conditions where it ferments natural
carbohydrates in plant products into ethanol.
v. This process is called fermentation.
B. In animals, the pyruvate is converted to lactate.
i. Lactate is produced mostly in muscles during strenuous exercise
because oxygen is used more than supplied leading to an oxygen debt.
ii. When oxygen is in short supply, NAD from glycolysis must be removed.
iii. So, each pyruvate molecule takes up the two hydrogen atoms from
reduced NAD to from lactate.
iv. The summary equation:
Pyruvate + reduced NAD lactate + oxidised NAD
This occurs in the absence of oxygen.
In aerobic respiration, neither the Krebs cycle nor the electron transfer chain can take
place. The only ATP that can be produced is formed by glycolysis.
In eukaryotic cells, anaerobic respiration occurs in:
A. In plants, and in microorganisms such as(yeast) where the pyruvate is converted
to ethanol and carbon dioxide.
i. The pyruvate molecule formed at the end of glycolysis loses one molecule
of carbon dioxide and then gains hydrogen from reduced NAD to produce
ethanol.
ii. The summary equation is:
Pyruvate + reduced NAD ethanol + carbon dioxide + oxidised NAD
iii. Used in the brewing industry, and ethanol is the important product.
iv. Yeast is grown in these anaerobic conditions where it ferments natural
carbohydrates in plant products into ethanol.
v. This process is called fermentation.
B. In animals, the pyruvate is converted to lactate.
i. Lactate is produced mostly in muscles during strenuous exercise
because oxygen is used more than supplied leading to an oxygen debt.
ii. When oxygen is in short supply, NAD from glycolysis must be removed.
iii. So, each pyruvate molecule takes up the two hydrogen atoms from
reduced NAD to from lactate.
iv. The summary equation:
Pyruvate + reduced NAD lactate + oxidised NAD
