Question

Assertion : A bacterial cell with restriction enzymes will be easily infected and lysed by bacteriophages.
Reason : Restriction enzymes catalyse synthesis of protective coat around bacterial cell that prevents bacteriophage attack.

Answer 1

Correct Answer - C
Restriction enzymes were named due to the phenomenon of host restriction of bacterial phages. Restriction enzymes produced in a bacterial cell, recognise and cleave foreign DNA introduced (such as from bacteriophage) into the cell. Thus, bacterial cell cannot beinfected and lysed by bacteriophage and hence a bacterial cell lacking restriction enzymes is easily susceptible to infection of phages. The DNA of the host bacterial cell is protected from its own restriction endonuclease by methylation (usually of A and C) within their reconginition sites.