Question

What are the changes that occur to cellular energy metabolism during metabolic rate suppression? Name and explain three important processes that are targeted for inhibition in this state.

Answer 1

Metabolic rate suppression is thought to be an important component to enhance survival in organisms during unfavourable conditions. This is very true for hibernating animals which escape months of unfavourable environmental conditions by suppressing their metabolic rates. Metabolic rate is also suppressed as a person ages or during crash dieting, starving or fasting.

During metabolic rate suppression the cell will produce less energy by oxidizing less amount of energy giving bio-molecules. The metabolic pathways - glycolysis, Kreb's cycle and oxidative phosphorylation will slow down.

Metabolism is divided into two gategories - catabolism and anabolism.

Catabolism is the breakdown of large molecules of nutrients into much simpler form so that they can be used by the body.

Anabolism is the process in which the smaller nutrient molecules are made into body building molecules like proteins and nucleic acids with the help of energy.

So, the three important metabolic processes which will be targetted by metabolic rate suppression will be - digestion of food, respiration and growth.

Digestion of food means breaking complex nutrients into smaller units so that they can be absorbed into the body and used by it for other purposes. Metabolic rate suppression will slow down this process.

Respiration is also categorised into two types - breathing, which is intake of oxygen and giving out CO2, and cellular repiration which involves using glucose in the cell to give out energy in the form of ATP. this energy is used by the body to perform all the other life functions. In fact, energy is needed for all biochemical or physical processes in living beings. So, slowing down of respiration will automatically slow down all other life processes.

Growth requires new molecules of proteins and nucleic acids. Low availability of energy will slow down the rate of protein synthesis by the cells which in turn will slow down growth.