Final answer:
Modifications to DNA that can cause mutations or interfere with replication or transcription include deamination of cytosine, oxidation of guanine, formation of thymine dimers from UV light, and DNA strand breaks from hydroxyl radicals.
Step-by-step explanation:
The potential modifications to DNA that can result in a mutation or interfere with replication or transcription include:
- Deamination of cytosine to uracil, which results in the replacement of a G-C base pair with an A-T pair after replication.
- The oxidation of guanine to 8-oxoguanine, leading to altered base-pairing properties and potentially causing mutations.
- The formation of thymine dimers, primarily due to UV light exposure, which can disrupt replication and transcription leading to frameshift or point mutations.
- Reaction with hydroxyl radicals causing DNA backbone strand breaks, interfering with the integrity of the DNA molecule.
These changes can be caused by both spontaneous reactions within the cell and from exposure to external agents such as UV light and chemicals. DNA has repair mechanisms like nucleotide excision repair that can correct some of these modifications, such as thymine dimers, to maintain genetic stability.