Is DNA Permanent?

No, DNA is not always permanent. While DNA is generally stable, changes can occur, though "only rarely do the cell's DNA-maintenance processes fail, resulting in permanent change in the DNA."

DNA Stability and Change

The survival of an individual organism depends on maintaining genetic stability. However, occasional genetic changes are necessary for the long-term survival of a species. This creates a tension between the need for accuracy and the need for adaptability.

• DNA Maintenance Processes: Cells have sophisticated mechanisms to ensure DNA is copied and maintained accurately. These processes include:

  • Proofreading: DNA polymerases, the enzymes responsible for replicating DNA, can "proofread" their work and correct errors as they go.
  • Mismatch Repair: This system identifies and corrects mismatched base pairs that were missed during proofreading.
  • Excision Repair: Damaged or modified bases are removed and replaced with the correct ones.

• Causes of DNA Change: Despite these mechanisms, DNA changes (mutations) can still occur:

  • Replication Errors: Although rare, DNA polymerases can make mistakes during replication.
  • DNA Damage: Exposure to environmental factors (e.g., UV radiation, chemicals) can damage DNA.
  • Transposons: These "jumping genes" can insert themselves into different locations in the genome, disrupting genes.

• Consequences of DNA Change:

  • Most changes have no effect, or are immediately repaired.
  • Some changes lead to a cell not functioning correctly.
  • Rare changes have a beneficial effect, such as increased immunity.

Factors Affecting DNA Permanence