question_answer 54)

  Enumerate the assumptions that we undertake in making the respiratory balance sheet. Are these assumptions valid for a living system? Compare fermentation and aerobic respiration in this context.

Oxidation of NADH to is slow process.

It is a vigorous reaction in aerobic respiration.

Answer:

                The calculations of the net gain of ATP for every glucose molecule oxidised can be made on the following assumptions (i) There is sequential pathway that follows, i.e., glycolysis, TCA cycle and ETS in cytoplasm, mitochondrial matrix and inner mitochondrial membrane respectively. (ii) NADH, synthesised in glycolysis enters in to ETC for phosphorylation. (iii) None of the intermediates in the pathway are utilised to synthesise any other compound. (iv) Glucose forms respiratory substrate. These assumptions are not valid for a living system because of following reasons (i) These all pathways work simultaneously and do not take place one after the other. (ii) ATP is utilised when needed. (iii) Rate Of enzyme actions is controlled by multiple means. Comparison between fermentation and aerobic respiration are as follows

Fermentation	Aerobic Respiration
Fermentation is partial breakdown of glucose.	It is complete breakdown of glucose.
Net gain of only 2 ATP.	38 ATP are produced.
Oxidation of NADH to is slow process.	It is a vigorous reaction in aerobic respiration.