Anaerobic respiration

• Bacteria and archaebacteria are organisms that can survive even in

  environments that are deprived of oxygen. so they undergo anaerobic
• fermentation is another anaerobic pathway used by most organisms when deprived of oxygen
• Fermentation undergoes glycolysis resulting in making ATP, NADH, and pyruvate.
• Fermentation undergoes glycolysis resulting in making ATP, NADH, and pyruvate.
• pyruvate molecules must undergo lactic acid or alcoholic fermentation to regenerate NAD+ without oxygen
• Lactate is produced in lactic acid fermentation
• ethanol is produced in alcoholic fermentation
• Lactic Acid Fermentation

  • pathway is common to obligate anaerobes, which cannot tolerate the presence of oxygen.
  • happens in muscle cells
  • pyruvate from glycolysis are converted to lactate through the enzyme lactate dehydrogenase
• The formation of lactic acid in our muscle cells causes muscle fatigue.
• Types of bacteria that undergoes Lactic acid fermentation

  1. homofermentative lactic acid bacteria (LAB)
  2. heterofermentative lactic acid bacteria (LAB)
• Homofermentative LAB is an organism that utilizes glucose molecules to produce lactic acid alone.
• heterofermentative LAB are organisms that produce ethanol and carbon dioxide along with lactic acid as their by-products.
• Alcoholic fermentation is a process by which organisms ferment glucose and produce ethanol as its by-product

  • used in bread and winemaking
• Alcoholic fermentation step 1

  1. Pyruvate molecules undergo decarboxylation which results in the formation of acetaldehyde.
• Alcoholic fermentation step 2

  2. Acetaldehyde is added with a hydride group from NADH and one hydrogen molecule which results in the formation of ethanol and oxidation of NADH to NAD+.