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Science and Technology › Basic science in news

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Biology in news

Biology as it reaches the news: DNA, RNA and proteins, cells, evolution and fossils, animal behaviour, the brain, immunity and ageing. Prelims has asked how plant and animal cells differ and what B cells and T cells do in the body.

Foundation note: Dominant and recessive alleles

DNA replication

Copy link to DNA replication

Prelims and Mains

DNA replication is the copying of a cell's deoxyribonucleic acid (DNA) before the cell divides, and that copying is mechanical work.

  • The two strands pair adenine with thymine and guanine with cytosine, so each is a template for the other.
  • The two strands are wound around each other and have to be pulled apart before either can be read: helicase spends adenosine triphosphate (ATP) to split the double helix, opening a Y shaped replication fork.
  • Topoisomerases release the twisting building ahead of the fork.

What changed

  1. 19 Aug 2026BriefThe study found a molecular safety catch that keeps the copying apparatus inactive until a chemical signal releases it. The Hindu, 19 Aug 2026: Helicase, the enzyme that unzips DNA (opens in a new tab)

Also filed elsewhere

  • Epigenetics · on Genomics, gene editing and cell therapy

    Epigenetics is heritable change in how active a gene is, without any change to the DNA sequence itself.