Anaerobic respiration

Glucose = Ethanol + Carbon Dioxide + Energy
C6H12O6 = 2C2H5OH + 2CO2 + ATP

OR

Glucose = Energy + Lactic acid

C6H12O6 = ATP + C3h6O3

Less energy is produced during anaerobic respiration as oxygen is not involved. Oxygen is a highly electronegative atom , and hence is a good electron acceptor. During anaerobic respiration , other acceptors such as nitrate and sulfate are used , they have a smaller reduction rate , causing less energy to be released per oxidized molecule of primary electron donor.

Lactic Acid(C3h6O3)

The lactic acid system is capable of releasing energy that can resynthesise ATP without the involvement of oxygen and is called anaerobic glycolysis. Glycolysis (breakdown of carbohydrates) results in the formation of pyruvic acid and hydronium ions (H+). The pyruvic acid molecules undergo oxidation in the mitochondrion and the Krebs Cycle begins. A build-up of H+ will make the muscle cells acidic and interfere with their operation so carrier molecules, called nicotinamide adenine dinucleotide (NAD+), remove the H+. The NAD+ is reduced to NADH that deposit the H+ at the electron transport gate (ETC) in the mitrochondria to be combined with oxygen to form water (H2O).To prevent the rise in acidity, pyruvic acid accepts H+ forming lactic acid that then dissociates into lactate and H+. Excess lactate can be removed by conversion to glucose via gluconeogenesis in the liver and then released back into the circulation.

Ethanol(C2H5OH)

Better known as alcohol , it is formed by ethanol fermentation during anaerobic respiration , a biological process in which sugars such as glucose and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products. Yeast produce alcohol using ethanol fermentation and it is also responsible for the rising of bread dough. Yeast organisms consume sugars in the dough and produce ethanol and carbon dioxide as waste products.