DNA replicates through a precise biological process that ensures each new cell receives an exact copy of the genetic material. This process occurs during cell division and involves several key steps:

Steps of DNA Replication

1. Initiation (Preparing for replication)

• DNA replication begins at specific locations on the DNA called origins of replication.
• An enzyme called helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds between base pairs, creating a Y-shaped structure called the replication fork.
• This separation exposes each strand to serve as a template for new DNA synthesis

2. Elongation (DNA synthesis)

• DNA strands are antiparallel, so replication occurs differently on each strand:
  • The leading strand is synthesized continuously in the 5' to 3' direction toward the replication fork.
  • The lagging strand is synthesized discontinuously in short fragments called Okazaki fragments away from the replication fork.
• DNA polymerase enzymes add complementary nucleotides (A pairs with T, and C pairs with G) to the exposed template strands.
• Primase synthesizes short RNA primers to provide starting points for DNA polymerase.
• On the lagging strand, multiple primers are used, and DNA polymerase synthesizes Okazaki fragments that are later joined together

3. Termination (Finishing the process)

• RNA primers are removed by exonuclease enzymes.
• DNA polymerase fills in the gaps with DNA nucleotides.
• DNA ligase seals the fragments into continuous strands.
• The two resulting DNA molecules each contain one original (parental) strand and one newly synthesized strand, making replication semi-conservative.
• The DNA rewinds into its double helix structure

Additional Details

• DNA replication occurs during the S phase of the cell cycle.
• Multiple proteins and enzymes coordinate the process, ensuring high fidelity with proofreading mechanisms to minimize errors.
• In eukaryotes, replication starts at multiple origins to complete the process efficiently, while prokaryotes typically have a single origin

This coordinated mechanism ensures that genetic information is accurately copied and passed on to daughter cells during growth, repair, and reproduction.