A restriction enzyme with a four-base recognition site would cleave DNA with a statistical frequency of once every
A) 4 base pairs.
B) 256 base pairs.
C) 4,096 base pairs.
D) 65.5 kilobases.

Question

Quizplus · Accepted Answer

A four-base recognition site means that the enzyme will only cut when it encounters a specific sequence of four nucleotides. There are 4 possible nucleotides (A, T, C, G), so the probability of finding a specific four-nucleotide sequence is 1/4^4, or 1/256. Therefore, the enzyme will cleave DNA with a statistical frequency of once every 256 base pairs.

A Restriction Enzyme with a Four-Base Recognition Site Would Cleave