मराठी
Tamil Nadu Board of Secondary EducationHSC Science Class 12

DNA Replication

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Estimated time: 3 minutes
Maharashtra State Board: Class 12

Key Points: DNA Replication

  • DNA replication is the process of synthesis of DNA from parental DNA, occurring in the S-phase of interphase and follows a semi-conservative mode.
  • It is semi-conservative, meaning each daughter DNA has one parental strand and one newly synthesized strand, as proved by Meselson and Stahl experiment (E. coli).
  • Replication begins at a specific site called the origin (Ori), where nucleotides are activated, and DNA unwinds using the enzyme helicase, forming a replication fork.
  • Single-strand binding proteins (SSB) stabilise separated strands, and RNA primers initiate synthesis of new strands.
  • DNA polymerase synthesizes new strands in the 5’ → 3’ direction, continuously on the leading strand and discontinuously on the lagging strand.
  • On the lagging strand, short DNA segments called Okazaki fragments are formed and later joined by DNA ligase.
  • RNA primers are removed and replaced by DNA, and finally, two identical daughter DNA molecules are formed.
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