MCQ Detailed View

DNA, or Deoxyribonucleic Acid, is a fundamental molecule found in the cells of all living organisms. It belongs to a class of nucleic acids, which are essential for storing and transmitting genetic information. DNA carries the instructions needed for the growth, development, functioning, and reproduction of every organism.

Structurally, DNA is composed of nucleotides, each consisting of a sugar (deoxyribose), a phosphate group, and a nitrogenous base. The four nitrogenous bases — adenine (A), thymine (T), cytosine (C), and guanine (G) — form complementary pairs (A with T, C with G) through hydrogen bonding. This pairing creates the famous double helix structure discovered by James Watson and Francis Crick in 1953.

DNA is located mainly in the cell nucleus, where it forms chromosomes, and in small amounts in mitochondria. It serves as the template for replication, ensuring that genetic information is accurately copied and passed to new cells during cell division. DNA also guides the synthesis of proteins through transcription and translation, controlling the traits and functions of the organism.

Unlike substances such as acetic acid or citric acid, which are simple chemical compounds involved in metabolism, DNA is a complex macromolecule that defines the blueprint of life. Without DNA, organisms would not be able to reproduce, repair tissues, or maintain cellular functions.

Understanding DNA is essential in biology, genetics, medicine, and biotechnology. It provides the basis for studying heredity, evolution, genetic disorders, and modern technologies like genetic engineering, DNA fingerprinting, and molecular diagnostics. In everyday science, DNA explains how traits are inherited and how life operates at the molecular level.

The correct answer is Option 2 — A class of nucleic acids, highlighting DNA’s role as the carrier of genetic information in all living beings.