Answer to Question #165677 in Molecular Biology for Virat

Question

2) After being in a solarium, a woman found an increase in the number of neoplasms on her skin. The cause 

of the neoplasm was a violation of the nucleotide sequence due to exposure to UV rays.

1. What changes in the DNA molecule occur under the influence of UV radiation?

2. What type of repairation corrects such damage? Schematic depict and explain.

Answer 1

The DNA molecule absorbs the UV light that results in the formation of the thymine dimers.

In humans, the base excision repair mechanism is used for this purpose. Following are the steps of this repair mechanism.

• The defect is first recognized by the 5'to 3' nuclease of the DNA polymerase I.
• The DNA polymerase enzyme then replaces the defective part with the correct bases.
• The defective part of the DNA is removed.
• DNA ligase seals the gap.