Question

A peptide bond is found in which type of biological molecule
(a) Carbohydrate
(b) Lipid
(c) Nucleic acid
(d) Protein

Answer 1

Hint: A peptide bond is formed when the carboxyl group of one molecule reacts with the amino group of another molecule with the elimination of water. Hence, this process is known as dehydration or condensation synthesis.

Complete Answer:
A peptide bond is formed between two amino acids when the amino group of one reacts with the carboxyl group of another amino acid. A peptide bond is a covalent bond and can be broken by hydrolyzing it. Amino acids join together by peptide bonds to form a polymer known as protein. Protein is very important for our body as it forms the structural components of our cells. Also, many enzymes that carry out metabolism in our body are proteinaceous in nature.

Additional information: Let us look at the different structures of protein in our body:
Primary structure: It is the sequence in which amino acids are arranged.
Secondary structure: It is associated with the local interactions between polypeptide chains which result in the formation of alpha-helix and beta-pleated sheet structures.
Tertiary structure: It is associated with the 3-D structure which is formed by the folding of secondary structures because of the interactions between the ‘R’ groups.
Quaternary structure: It is associated with the orientation and arrangement of multiple tertiary subunits that are present in one protein structure.
So, the correct option is ‘(d) Protein’.

Note:
- Carbohydrates are formed by monosaccharides joining together through glycosidic bonds.
- Lipids are formed by the combination of glycerol and fatty acids.
- Nucleic acids are made by the monomer nucleotide which is joined by a phosphodiester bond.