The intact DNA is copied from one cell to another.sometimes error occurred in this process which leads to mutations.

Cell Reproduction and DNA Replication
When a cell reproduces, its DNA undergoes a precise and vital process known as DNA replication. This ensures that each new cell receives an exact copy of the genetic material.
Phases of DNA Replication
- Interphase
- Before cell division, the cell is in interphase, where it prepares for replication. This includes the synthesis phase (S phase), when DNA is replicated.
- Unwinding the DNA
- The double helix structure of DNA unwinds and separates into two strands. This is facilitated by enzymes called helicases.
- Base Pairing
- Each strand serves as a template. DNA polymerases add complementary nucleotides to each strand. Adenine pairs with thymine, and cytosine pairs with guanine.
Proofreading and Error Correction
- Proofreading Mechanism
- DNA polymerases have proofreading capabilities to correct any mistakes during replication, ensuring high fidelity.
- Repair Enzymes
- Additional repair enzymes fix any errors that escape proofreading, maintaining the integrity of the DNA.
Final Steps of Replication
- Formation of Two Identical DNA Molecules
- At the end of replication, two identical DNA molecules are formed, each consisting of one original strand and one newly synthesized strand (semi-conservative replication).
- Preparation for Cell Division
- The replicated DNA condenses into chromosomes, and the cell is now ready to undergo mitosis or meiosis, leading to cell division.
Importance of DNA Replication
- Genetic Consistency
- Accurate DNA replication is crucial for the continuity of genetic information across generations of cells.
- Cell Functionality
- Ensures that all cellular functions can be carried out effectively by providing the necessary genetic instructions.