Summary
Unrepaired DNA damage becomes permanent mutation after replication, driving cancer and ageing.
In depth
Spontaneous damage such as deamination and oxidation happens thousands of times per cell per day. Repair fixes most. When repair fails or is overwhelmed, mutations arise, and accumulate over a lifetime.
Carcinogens such as tobacco smoke and UV create characteristic mutation signatures.
Mutations also come from replication errors (about 1 in 100,000 before repair), from reactive oxygen species (8-oxoguanine), and from endogenous methylating agents. Exposure to UV light yields thymine dimers; tobacco smoke leaves characteristic benzopyrene adducts in p53; and aflatoxin from mould causes a specific G to T mutation in liver cancer. Mutational signatures in tumour genomes show the history of exposure and repair defects.
Because repair is not perfect, the balance between damage, repair and cell cycle checkpoints sets the mutation rate. Mutator phenotypes, such as in mismatch repair deficiency, drive cancer evolution.
Key idea: cells with unrepaired damage are either arrested, killed through apoptosis or live on with mutations.
Frequently asked questions
What is Mutation and Repair Link?
Unrepaired DNA damage becomes permanent mutation after replication, driving cancer and ageing.
Which area of biology covers Mutation and Repair Link, and how advanced is it?
Mutation and Repair Link is one of the 52 topics in Molecular Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include DNA Repair, DNA Replication, DNA Methylation.
Can you give an example of Mutation and Repair Link?
UV causes C to T changes at pyrimidine dimers in skin cancers.
What should I learn before Mutation and Repair Link?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to Mutation and Repair Link. Intermediate topics assume the Beginner vocabulary.
What topics are related to Mutation and Repair Link?
The closest topics to Mutation and Repair Link are DNA Repair, DNA Replication, DNA Methylation, Transcription Factors. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Mutation and Repair Link?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Mutation and Repair Link. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is Mutation and Repair Link different from DNA Repair?
Mutation and Repair Link: Unrepaired DNA damage becomes permanent mutation after replication, driving cancer and ageing. DNA Repair: Mechanisms such as mismatch, excision and double-strand break repair that fix errors and damage in DNA. Read both side by side and note what each one explains.
How should I study Mutation and Repair Link step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with DNA Repair and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.