Reactions leading to the formation of amino acids from the TCA cycle intermediates:

The correct option is 'C', transamination.

Explanation:

The TCA (tricarboxylic acid) cycle, also known as the citric acid cycle or Krebs cycle, is a series of chemical reactions that occur in the mitochondria of cells. It is an essential metabolic pathway that generates energy in the form of ATP and provides intermediates for various biosynthetic pathways, including the formation of amino acids.

Transamination:
Transamination is a key reaction in amino acid metabolism, where an amino group (-NH2) is transferred from an amino acid to a keto acid, resulting in the formation of a new amino acid and a new keto acid. In the context of the TCA cycle, transamination reactions play a crucial role in the synthesis of amino acids from TCA cycle intermediates.

Role of transamination in amino acid synthesis:
1. α-Ketoglutarate (an intermediate of the TCA cycle) can be transaminated to form glutamate. This reaction is catalyzed by the enzyme glutamate dehydrogenase.
2. Glutamate can further undergo transamination to form other amino acids. For example:
- Transamination of glutamate with oxaloacetate forms aspartate, catalyzed by the enzyme aspartate aminotransferase.
- Transamination of glutamate with pyruvate forms alanine, catalyzed by the enzyme alanine aminotransferase.
- Transamination of glutamate with 3-phosphoglycerate forms serine, catalyzed by the enzyme phosphoserine aminotransferase.

These transamination reactions allow the conversion of TCA cycle intermediates into amino acids, which are essential building blocks for proteins and play vital roles in various biological processes. The newly formed amino acids can then be utilized for protein synthesis or other metabolic pathways.

In summary, transamination reactions play a crucial role in the formation of amino acids from TCA cycle intermediates. They facilitate the transfer of amino groups from TCA cycle intermediates to keto acids, resulting in the synthesis of different amino acids.