Question

(1200 word report) Give an overview of the biochemical events that occur at the start point of the running race (that is, before the runner has commenced running), after 5 minutes and after 45 minutes, in terms of:

● the processes involved in the mobilisation and/or use of both types of fuels (carbohydrates and lipids).

● a brief overview of the biochemical pathways used to degrade these fuel molecules

● a comparison of the yield of ATP for both fuels

Answer 1

Biochemical events taking place in the running race -

A) Process involved in Fuel mobilisation -

• The source fuels for energy are carbohydrates , lipids , lactates etc.
• The fuel metabolism is important for meeting the energy requirement of the body.
• The carbohydrate is the major source of energy which is obtained from sugars , starch , fibres which are found in vegetables , fruits and milk products. It has six functions - provides energy, regulates blood sugar level , spares the protein breakdown for energy, break-down of fatty acids, provides dietary fiber and it also contributes to natural sweetener for foods.The carbohydrate mobilisation takes place by glycolysis.
• Lipids are the hydrocarbon chains that forms the building block of structure and function of the cells.The lipid mobilisation takes place by lipolysis.

B)The biochemical pathways for breakdown of carbohydrates and lipids are -

Glycolysis - The breakdown of carbohydrates into simpler substances . Glycolysis can take place either in the presence of oxygen or in the absence of oxygen.The glycolysis takes place in cytoplasm of the cell. The output products of glycolysis are two molecules of pyruvate, two molecules of ATP, two molecules of NADH, and two molecules of water.

Lipolysis - The process of breakdown of fat to yield energy is called as lipolysis. Lipolysis takes place in the cytoplasm. In lipolysis triglycerides are broken down into free fatty acids .Digestion of fats begin in the mouth through chemical digestion by lingual lipase.

C) In case of lipids, an 18 carbon fatty acid (stearic acid) yields 146 ATPs, while a 20 carbon fatty acid will yield 163 ATPs.

In case of carbohydrates 1g of carbohydrates is equal to 4 calories of energy. In contrast to carbohydrates, lipids yield 9kcal/gram.