Answer the question on basis of the passage given below:

In zwitter ionic form, amino acids show amphoteric behaviour as they react both with acids and bases.

Except glycine, all other naturally occurring \(\alpha \)- amino acids are optically active, since the \(\alpha \)-carbon atom is asymmetric. These exist both in 'D' and 'L' forms. Most naturally occurring amino acids have L-configuration. L-amino acids are represented by writing the \(NH_2\) group on the left hand side.

Which of the following amino acid is essential?

Valine

The correct answer is option 4. Valine.

Amino acids are the building blocks of proteins. They play critical roles in various biological processes, including protein synthesis, enzyme function, and neurotransmitter regulation. Amino acids are categorized into two main groups: Essential Amino Acids and Non-Essential Amino Acids.

Essential Amino Acids

Essential amino acids cannot be synthesized by the human body in sufficient quantities and must be obtained from dietary sources. Essential amino acids are vital for protein synthesis, enzyme production, and overall body function. They play roles in muscle repair, hormone production, and maintaining nitrogen balance. List of Essential Amino Acids: For humans, the essential amino acids include: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine

Non-Essential Amino Acids

Non-essential amino acids can be synthesized by the body from other compounds, so they do not need to be obtained directly through the diet. While still important, non-essential amino acids are not required to be included in the diet because the body can produce them as needed. Examples: Glycine, Glutamic Acid (Glutamate), Alanin

Detailed Analysis of Each Option

1. Glycine:

Classification: Non-Essential

Glycine is the simplest amino acid and is involved in the synthesis of proteins, nucleic acids, and other important molecules. The body can produce glycine from other amino acids, so it does not need to be obtained from the diet.

2. Glutamic Acid:

Classification: Non-Essential

Glutamic acid is involved in protein synthesis and cellular metabolism. It also acts as a neurotransmitter in the brain. The body can synthesize glutamic acid, making it non-essential.

3. Alanine:

Classification: Non-Essential

Alanine is involved in energy production and metabolism. Like glycine and glutamic acid, alanine can be synthesized by the body, so it is classified as non-essential.

4. Valine:

Classification: Essential

Valine is a branched-chain amino acid (BCAA) that is important for muscle metabolism, tissue repair, and nitrogen balance. Since the body cannot synthesize valine, it must be obtained through dietary sources such as meat, dairy products, and legumes.

Conclusion: Valine is classified as an essential amino acid because it cannot be produced by the human body and must be acquired through the diet. In contrast, glycine, glutamic acid, and alanine are non-essential because the body can synthesize them from other compounds.

Thus, the correct answer is 4. Valine.