Chemistry 2 Marks Questions

A polypeptide bond, commonly referred to as a peptide bond, is formed through a biochemical process known as dehydration synthesis or condensation reaction. A polypeptide bond is formed when the carboxyl group of one Amino acid reacts with the amino group of another amino acid releasing a molecule of water and forming a covalent bond between the two amino acids. This bond is the basis for the formation of proteins, which are composed of one or more long chains of polypeptides.

Technique of DNA fingerprinting is used in :
(i) To determine the paternity of an individual.
(ii) To identify the racial groups to rewrite biological evolution.
(iii) In forensic laborateries for the identification of criminals.
(iv) To identify dead bodies by comparing the DNAs of parents and children.

(i) Essential Amino Acids: The amino acids which are required for proper growth and development and health and supplied through diet are known essential amino acids. For example, valine, leucine, proline etc.
(ii) Non-essential Amino Acids: Non-essential amino acids are those which are produced in human body. Example: Proline, Glycine, Serine.

Proteins are very sensitive to the action of heat, mineral acids, alkalies etc. on heating or on treatment with mineral acids globular proteins (soluble proteins) often undergo coagulation or precipitation to give fibrous proteins which are insoluble in water and as a result proteins loss their biological activities. Chemically, denaturation does not change the primary structure but brings about changes in the secondary and tertiary structure of proteins.