Question

What is a thymine dimer?

Multiple choice question.
A. A mutation caused by a chemical mutagen that causes a thymine base to pair with another thymine instead of adenine
B. A location in a DNA molecule where there are two thymine bases in a row
C. A thymine analogue that can be incorporated into a DNA molecule during replication, leading to mutation
D. A site where two adjacent thymine bases become covalently cross-linked to each other

Answer 1

A thymine dimer is a form of DNA damage where two thymine bases adjacent to each other on a DNA strand become covalently bonded after UV exposure. This can cause replication errors if not repaired. The repair mechanism is known as nucleotide excision repair.

Step-by-step explanation:

A thymine dimer is a type of DNA damage where two adjacent thymine bases on a DNA strand become covalently linked to each other as a result of exposure to ultraviolet (UV) light. This cross-linking can lead to significant issues during DNA replication and transcription because the normal base pairing is disrupted, and if left unrepaired, may lead to mutations such as frameshift or point mutations. Cells can repair thymine dimers through a process known as nucleotide excision repair, where enzymes recognize the dimer, remove it, and replace it with the correct bases.