Which intermediate compound is involved in the synthesis of amino acids?
A. Malic acid
B. Citric acid
C. Alpha-ketoglutaric acid
D. Isocitric acid

Hint: Intermediate compound is the compound which is produced in the course of the chemical reaction which is not a final product but is used in further reaction in order to produce the final product. Intermediate compound is also called as the synthetic intermediate, or intermediate product.

Complete Answer:
- Amino acids are the structural units that make the polymer called protein.
- Amino acids contain an amine, carboxyl, and functional group with a side chain. Side chain is specific to each amino acid.
- The key elements of the amino acids are Carbon, Nitrogen, Oxygen and Hydrogen. There are a total of 20 amino acids present which make thousands of proteins.
 Example of amino acids include Cystine, Glycine, Valine, Alanine, etc

Synthesis of amino acids:
- Amino acid synthesis is the set of biochemical reactions by which amino acids are produced.
- The substrate for the amino acid synthesis is the diet or growth media of any organism.
- Not all the organisms are capable of producing amino acids. Humans can synthesise only 11 to 20 amino acids.
- The pathway of production of amino acids is quite simple. Amino acids are formed by the transamination reaction.
- Glutamate dehydrogenase catalyzes the reductive amination of alpha-ketoglutaric acid to glutamate.
- So, alpha-ketoglutaric acid is the intermediate compound in the synthesis of amino acids.

Hence, option C is the correct option for this question.

Note: Amino acids are of two types –
1. Essential amino acids – These types of amino acids do not produce in the body. They must be present in our diet.
2. Non-essential amino acids – These amino acids are produced by the body itself.