Question

Eco ri and rsa i restriction endonucleases require 6 bp and 4 bp sequences respectively for cleavage. In a 10 kb dna fragment how many probable cleavage sites are present for these enzymes?

Answer 1

1 kb consists of 1000 bp

The DNA fragment here made up of 10 kb which is equal to 10000 (10 × 1000) bp

The number of cleavage sites could be estimated by using probability formula:

$(1/4)^n$ × 10000

where n is the required number of base pair for cleavage

Cleavage sites for Eco Ri restriction endonucleases:

n=6

= $(1/4)^6$  × 10000

= $0.25^6$ × 10000

= 0.00024  × 10000

= 2.4

~ 2 cleavage sites

Cleavage sites for Rsa i restriction endonucleases:

n=4

=$(1/4)^4$ × 10000

=$(0.25)^4$ × 10000

= 0.003906 × 10000

= 39.06

~ 39 clevage sites

Answer 2

first answer is absolutely correct ✔️