Question

Which of the following is not true for type 1 restriction endonuclease?

(a) It is a single enzyme with 3 subunits

(b) Using it is an energy requiring process

(c) Methylation and cleavage occurs in the same sequence

(d) The cleavage is up to 1000bp away

The question was asked in an online interview.

The query is from Restriction Endonuclease topic in section Genomics : The Mapping and Sequencing of Genomes of Cytogenetics

Answer 1

The correct choice is (c) Methylation and cleavage occurs in the same sequence

For explanation: Type 1 restriction endonuclease recognizes and cleaves at different points. While it methylates at the recognition sequence, the cleavage could be as far as 1000bp. Also both these processes require ATP.