Question

What are respiratory substrates? Name the most common respiratory substrate.

Answer 1

Hint: ATP stands for Adenosine Triphosphate and it is commonly known as the energy currency of the cell. During the synthesis of ATPs various respiratory substrates are formed.

Complete Answer:
The respiratory substrate is the compounds that are oxidised during the process of respiration. It is used by all the living cells to liberate energy. The common respiratory substrates are carbohydrates, especially glucose, which act as a respiratory substrate. Fats, proteins, and organic acids can also act as respiratory substrates depending upon the physiological condition of the body of an organism.

Fats are used by a number of organisms as they contain more energy as compared to carbohydrates. However, the fats are not used directly instead they are first broken to intermediates common to glucose oxidation, viz. acetyl CoA, glyceraldehyde phosphate.

Proteins are used in respiration rarely as during the germination of protein-rich seeds and spores. Proteins are also used as respiratory substrates under the starvation condition when carbohydrates and fats become unavailable.
Respiration that involves proteins as respiratory substrates are called protoplasmic respiration while fats and carbohydrates are used respiratory substrates are called floating respiration.

Note: It is to be noted that fats, proteins, and organic acids can also act as respiratory substrates depending upon the physiological condition of the body of an organism.