Problem 44 - A Complete Resource Book in Chemistry for JEE Main

Question

Peptides are formed from (a) aliphatic amines (b) carbohydrates (c) \(\alpha\)-amino acids (d) aromatic amines

Step-by-Step Solution

Answer

Peptides are formed from \( \alpha \)-amino acids, option (c).

Step 1: Understand the Concept of Peptides

Peptides are short chains of amino acids linked by peptide bonds. They are smaller than proteins and are formed through the polymerization of amino acids. Understanding that amino acids are the building blocks of peptides is crucial to answer this question.

Step 2: Identify Components that Form Peptides

Peptides specifically form from amino acids, more specifically \( \alpha \text{-amino acids} \). An \( \alpha \text{-amino acid} \) consists of an amine group, a carboxylic acid group, a hydrogen atom, and a variable R group all attached to the same carbon atom, known as the \( \alpha \) carbon.

Step 3: Evaluate the Choices

Let's look at the options:- (a) aliphatic amines: These are not amino acids; they primarily contain a simple amine group.- (b) carbohydrates: These are different biomolecules not involved in forming peptide bonds.- (c) \( \alpha \)-amino acids: These are the building blocks of peptides.- (d) aromatic amines: These contain an aromatic ring and are not considered \( \alpha \)-amino acids.

Step 4: Choose the Correct Answer

After evaluating the options, we see that \( \alpha \)-amino acids are the components that form peptides. This matches option (c), confirming that \( \alpha \)-amino acids are necessary for peptide formation.

Key Concepts

Amino Acids

Amino acids form the fundamental building blocks of peptides and proteins. They are organic molecules that have both an amine group (urst, a nitrogen atom connected to hydrogen) and a carboxylic acid group (ring, represented by \( \text{COOH} \)). These groups are attached to the same central carbon atom, also known as the \( \alpha \) carbon.
Attached to this \( \alpha \) carbon are also a hydrogen atom and a variable R group, which gives each amino acid its unique properties.
Amino acids can be divided into various categories based on the nature of the R group, such as polar, nonpolar, acidic, or basic.
These differences create the vast versatility and range of functions peptides and proteins can perform in biological systems.

• Composed of an amine group, a carboxylic acid group, a hydrogen atom, and an R group.
• Vary based on the R group, affecting their behavior and role in proteins.

Peptide Bonds

Peptide bonds are the chemical links that hold amino acids together in a chain to form peptides and proteins. These bonds are created through a dehydration synthesis reaction, which involves removing a molecule of water from between two amino acids.
When two amino acids bond, the amine group of one reacts with the carboxylic acid group of the other, releasing a water molecule in the process. This reaction forms a bond known as the amide bond or peptide bond, characterized by the linkage between a carbon atom and a nitrogen atom.

• Essential for linking amino acids into peptides and proteins.
• Formed through a dehydration (loss of water) reaction between amino acids.
• Connects the carbon and nitrogen atoms of successive amino acids.

Polymerization

Polymerization in the context of peptides refers to the process of linking multiple amino acids together through peptide bonds to form a peptide chain. This process mirrors the general concept of polymerization, where small units, or monomers, join to form a polymer.
In peptide polymerization, each amino acid acts as a monomer. Through successive peptide bonds, a linear chain or polymer is created, which can further fold into complex structures to form functional proteins.
These steps of polymerization contribute to the diversity of biological functions that proteins and peptides can perform.

• Involves linking multiple amino acids to form chains.
• Peptide chains can further fold into diverse structures.
• Crucial for forming the complex structures and functions observed in proteins.