Answer the question on the basis of the passage given below:

Proteins are the polymers of about twenty different \(\alpha \)-amino acids which are linked by peptide bonds. Proteins perform various structural and dynamic functions in the organisms. Proteins which contains only \(\alpha \)- amino acids are called simple proteins. The secondary or tertiary structures of proteins gets disturbed on change of pH or temperature and they are not able to perform their functions. This is called denaturation of proteins. Enzymes are biocatalysts which speed up the reactions in bio systems. Vitamins are accessory food factors required in the diet. They are classified as fat soluble (A, D, E and K) and water soluble (B and C). Deficiency of vitamins leads to many diseases. Nucleic acids are the polymers of nucleotides which in turn consists of a base, a pentose sugar and phosphate moiety. Nucleic acids are responsible for the transfer of characters from parents to offspring’s. There are two types of nucleic acids: DNA and RNA. DNA contains a five carbon sugar molecule called 2-deoxyribose whereas RNA contains ribose.

Which of the following is an essential amino acid?

Leucine

The correct answer is (1) Leucine.

Amino Acids:
Amino acids are the building blocks of proteins, which are essential for the structure and function of the human body. There are 20 standard amino acids commonly found in proteins, and they can be categorized into two groups based on how they are obtained:

1. Essential Amino Acids: These are amino acids that the human body cannot synthesize on its own, meaning they must be acquired through the diet. There are nine essential amino acids.

2. Non-Essential Amino Acids: The body can synthesize these amino acids from other compounds and, therefore, they are not strictly required in the diet. There are 11 non-essential amino acids.

Leucine: An Essential Amino Acid:
Leucine is one of the nine essential amino acids. It plays a crucial role in various physiological processes in the body. Here are some key points about leucine:

Structure:  Leucine is an α-amino acid, which means it has an amino group (-NH₂) and a carboxyl group (-COOH) bonded to the same carbon atom, known as the alpha carbon (α). It also has a side chain that consists of a branched hydrocarbon group.

Function:  Leucine is primarily known for its role in protein synthesis. It is involved in the initiation of translation, a process in which the genetic code stored in messenger RNA (mRNA) is used to assemble proteins. Leucine helps activate the protein synthesis machinery in cells, making it a crucial component of muscle protein synthesis and the overall growth and repair of tissues.

Branched-Chain Amino Acid (BCAA):  Leucine is often grouped with two other amino acids, isoleucine, and valine, to form the class of branched-chain amino acids (BCAAs). BCAAs are important for various aspects of metabolism, particularly in muscle tissue. They can be used as an energy source during exercise and also play a role in reducing muscle soreness and fatigue.

Dietary Sources:  Leucine can be obtained through dietary sources such as meat (particularly red meat and poultry), dairy products, eggs, and legumes like soybeans and lentils.

Supplementation:  Some athletes and bodybuilders use leucine supplements to enhance muscle growth and recovery. Leucine supplementation is often combined with other BCAAs to support physical performance and muscle health.

In summary, leucine is an essential amino acid that plays a crucial role in protein synthesis, muscle growth, and various metabolic processes in the body. It must be obtained through the diet because the human body cannot synthesize it. Dietary sources rich in leucine include meat, dairy, eggs, and certain plant-based foods.