Question

Correct statement about restriction endonuclease.

(I) It is the enzyme which cuts $\text{DNA at}$ a particular point.

(II) The first restriction endonuclease was $\text{HindII.}$

(III) Overall, $\text{900}$ restriction enzymes have been isolated from about $\text{200}$ strains.

(IV) Each restriction endonuclease recognizes a specific palindromic sequence.

• A. I and IV are correct
• B. I and II are incorrect
• C. I and III are incorrect
• D. I, II, and IV are correct.

Answer 1

Answer: (D)

The first restriction endonuclease HindII whose functioning ws found to be dependent on a specific DNA nucleotide sequence was isolated and characterized 5 years later. It was found that HindII always cuts DNA molecules at a particular point by recognizing a specific sequence of six base pairs. This specific base sequence is known as the recognition sequence for HindII. Besides Hind II, today we know more than 900 restriction enzymes that have been isolated from over 230 strains of bacteria, each of which recognizes different recognition sequences. Each restriction endonuclease recognizes a specific palindromic sequence.