How Cells Copy and Fix Their DNA

Every time a cell divides, it must make an exact copy of its DNA—a process known as DNA replication. Specialized enzymes like DNA polymerase unwind and copy the DNA, ensuring genetic information is faithfully passed to the next generation.

Steps of DNA Replication

1. Unwinding: Helicase unzips the double helix.
2. Base Pairing: DNA polymerase adds complementary nucleotides.
3. Joining: Ligase connects the fragments (especially on the lagging strand).

DNA Repair Mechanisms

DNA can be damaged by UV light, chemicals, or errors during replication. Cells use repair pathways such as:

• Mismatch repair
• Nucleotide excision repair
• Homologous recombination

These mechanisms help prevent mutations, which can lead to cancer if left unchecked.

Real-World Relevance

Many cancer treatments target DNA replication or repair—highlighting the importance of these processes in medicine.