Q.33 The statistical frequency of the occurrence of a particular restriction enzyme cleavage site that is 6
bases long can be estimated to be
(A) once every 24 bases (B) once every 256 bases
(C) once every 1024 bases (D) once every 4096 bases
Why 4096 Bases?
DNA consists of four bases (A, T, C, G), so a specific 6-base sequence has 46 = 4096 possible combinations. In random DNA, this site occurs once every 4096 bases on average.
Option Analysis
- (A) Once every 24 bases: Incorrect; 24 equals 42 × 1.5, not matching any standard cutter length and too frequent for 6 bases.
- (B) Once every 256 bases: Wrong; 256 is 44, typical for 4-base cutters like TaqI, not 6-base ones.
- (C) Once every 1024 bases: Incorrect; 1024 is 210 or roughly 45, suiting 5-base sites but not exactly 6.
- (D) Once every 4096 bases: Correct, as 46 = 4096 precisely estimates frequency for hexanucleotide sites like EcoRI.
