Final answer:
The difference between the two sequences is a single nucleotide change, which is a type of point mutation known as a single nucleotide polymorphism (SNP). UV light can cause mutations like thymine dimers, which can be fixed by DNA repair mechanisms such as nucleotide excision repair.
Step-by-step explanation:
The difference between the two DNA sequences is in the second nucleotide triplet, where Sequence 1 has the bases 'GCA' and Sequence 2 has 'GAA'. This change represents a single nucleotide polymorphism (SNP), which is a type of point mutation. A point mutation is a mutation that affects a single nucleotide in the DNA sequence. In this case, the cytosine (C) in Sequence 1 is replaced by an adenine (A) in Sequence 2.
Regarding the DNA fragments exposed to UV light, UV exposure can cause thymine dimers to form, leading to errors during DNA replication. DNA repair mechanisms, such as nucleotide excision repair (NER), can correct these mutations. NER specifically recognizes and removes thymine dimers and other types of DNA damage that distort the DNA helix, allowing the correct nucleotides to be inserted.