1. DNA Unwinds and Separates:
- The double helix of DNA unwinds, and the two strands separate, like a zipper being unzipped. This is facilitated by enzymes like helicase.
2. DNA Replication Begins:
- Each separated strand acts as a template for the creation of a new complementary strand.
- Enzymes called DNA polymerases move along the template strand, adding nucleotides (building blocks of DNA) one by one, following base pairing rules (A with T, C with G).
3. Two Identical DNA Copies:
- As DNA polymerase works, two identical DNA molecules are produced. Each new DNA molecule consists of one original strand and one newly synthesized strand (this is called semi-conservative replication).
4. Chromosomes Form:
- The replicated DNA molecules condense into compact structures called chromosomes. Each chromosome now contains two identical copies of the DNA molecule, called sister chromatids. They are held together at a region called the centromere.
Why is DNA replication important?
* Ensures each daughter cell receives a complete set of genetic information: This is crucial for maintaining the genetic integrity of the organism.
* Allows for growth and development: By creating new cells, mitosis enables organisms to grow and develop.
* Replaces damaged cells: Mitosis also helps repair damaged tissues by producing new cells to replace the damaged ones.
In summary, DNA replication is a crucial step before mitosis, ensuring that each daughter cell receives a complete and accurate copy of the genetic material, allowing for the proper functioning and growth of the organism.
