Question: Why does a bubble form around the DNA during nucleotide excision repair?
Solution (explanation):
Remember that t nucleotide excision repair is a pathway used to remove and replace damaged bases. Nucleotide excision repair detects and corrects types of damage that distort the DNA double helix. In fact, in this process, the damaged nucleotides are removed along with a surrounding patch of DNA. In this process, a helicase (DNA-opening enzyme) cranks open the DNA to form a bubble, and DNA-cutting enzymes chop out the damaged part of the bubble. A DNA polymerase replaces the missing DNA, and a DNA ligase seals the gap in the backbone of the strand.
Answer: we can conclude that the correct answer is:
In nucleotide excision repair, a helicase opens the DNA to form a bubble, and enzymes that cut the DNA cut out the damaged part of the bubble. Then, damaged bases are cut within a nucleotide chain and replaced with DNA according to the instructions of the undamaged template strand. This repair system is used to remove pyrimidine dimers formed by UV radiation, as well as nucleotides modified by bulky chemical adducts.