Final answer:
The mutations in the man's eye cells caused by UV exposure are not inheritable because they occur in somatic cells, not reproductive germ cells. UV light damages DNA through the formation of pyrimidine dimers, and in humans, these are repaired by nucleotide excision repair.
Step-by-step explanation:
The doctor's claim that the mutations caused by ultraviolet (UV) light in the man's eye cells will not be passed on to future offspring is based on the understanding that UV light primarily affects somatic cells, which are any cells in the body that are not sperm or egg cells. Since only genetic information in the sperm or egg cells (germ cells) can be passed to offspring, mutations in somatic cells remain within the individual and are not heritable.
UV radiation can cause damage to DNA through the formation of pyrimidine dimers, particularly between thymine and cytosine. In humans, the initial mechanism for repairing such nucleotide errors in DNA is nucleotide excision repair. Although humans lack the photolyase enzyme, nucleotide excision repair is a complex, multi-step process by which a segment of the damaged DNA strand is removed and replaced with the correct sequence using the complementary strand as a template.