Question

How many ATP molecules are produced during respiration?

Answer 1

Hint: Respiration is a multi step enzyme mediated biochemical process of oxidative breakdown of organic compounds inside living cells. It is a process in which energy packets are released at different steps during different processes. The energy liberated during various steps is stored in the form of ATP, which is also known as energy currency of the body.

Complete answer:
Cellular respiration is a mechanism of breakdown of food materials within the cell to release energy and trapping this energy by the synthesis of ATP. During the process of respiration C-C bonds of complex bonds are broken down. The compounds that are oxidised during this process are known as respiratory substrates.
38 ATP molecules are synthesized by oxidation of one glucose molecule during cellular respiration. 4 ATP molecules are released during glycolysis and 2 ATP is utilised during the process. So net gain of ATP during glycolysis is 2. Two ATP molecules are formed from the Krebs cycle, and about 34 from the electron transport system. However, this maximum yield is never quite reached because of losses due to leaky membranes as well as the expense of moving pyruvate and ADP into the mitochondrial matrix.
When energy is required in the body, ATP decomposes to form ADP and inorganic phosphate releasing the energy suspended in them.

Note:
The energy trapped in the ATP molecules is utilised in various energy-requiring processes of the organisms, and the carbon skeleton produced during respiration is used as the precursor for biosynthesis of other molecules in the cell. The ATP is broken down whenever or wherever energy needs to be utilised.