Question

Match the type of DNA repair mechanism in Group I with the enzyme(s) involved in Group II

Group I	Group II
P) Mismatch repair	1) DNA glycosylase
Q) Base excision repair	2) UvrA, UvrB, UvrC and UvrD
R) Nucleotide excision repair	3) RecA
S) Double strand break repair	4) MutL, MutS and MutH

• A. P-4, Q-1, R-3, S-2
• B. P-4, Q-2, R-1, S-3
• C. P-4, Q-1, R-2, S-3
• D. P-2, Q-1, R-4, S-3

Answer 1

The Correct Option is C

To solve this question, we will match each DNA repair mechanism listed in Group I with the corresponding enzyme(s) listed in Group II based on their functions and roles in the repair process.

1. Mismatch Repair (MMR) - This repair mechanism is primarily responsible for correcting errors that escape proofreading during DNA replication. It identifies and repairs non-complementary base pairs. The key enzymes involved in prokaryotic mismatch repair are MutL, MutS, and MutH. Hence, P) Mismatch repair matches with 4) MutL, MutS, and MutH.
2. Base Excision Repair (BER) - This pathway is crucial for repairing small, non-helix-distorting base lesions. The initial step involves recognition of the erroneous base by an enzyme called DNA glycosylase, which excises the base, triggering further repair steps. Thus, Q) Base excision repair matches with 1) DNA glycosylase.
3. Nucleotide Excision Repair (NER) - This mechanism repairs bulky helix-distorting DNA lesions, such as thymine dimers caused by UV radiation. The enzymes involved in prokaryotic NER are UvrA, UvrB, UvrC, and UvrD, which help to cut and remove the damaged section. Therefore, R) Nucleotide excision repair matches with 2) UvrA, UvrB, UvrC, and UvrD.
4. Double Strand Break Repair (DSBR) - This repair is crucial for fixing breaks that affect both DNA strands. The enzyme RecA plays a significant role in homologous recombination, a pathway for double strand break repair in prokaryotes. Hence, S) Double strand break repair matches with 3) RecA.

By mapping each mechanism to its corresponding enzyme(s), the correct pairing for the options given is P-4, Q-1, R-2, S-3.