Question

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.

Answer 1

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, mitochondria] 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 fora living system because of following reasons
(i) These all pathways work simultaneously and do not take place one after the other.
(ii) ATP is utilis.ed when needed.
(iii) Rate of enzyme actions is controlled by multiple means.
Comparisan between fermentation and aerobic respiration are as follows
$\begin{array}{cc}\text{Fermentatin}& \text{Aerobic Respiration}\\ \text{Fermentation is partial breakown of glucose.}& \text{It is complete breakdown of glucose}\\ \text{Net gain of only 2 ATP.}& 38\text{ATP are produced.}\\ \text{Oxidation of NAOH to}NA{D}^{+}\text{is slow process.}& \text{It is a vigorous reaction in aerobic respiration}\end{array}$