Question

The role of restriction enzymes in bacteria is

A) to protect the cell from invading phages
B) to provide the cell with new phenotypes
C) to allow transposons to move to another place in the chromosome
D) to make conjugation more efficient
E) to allow cells to accept foreign DNA

Answer 1

In bacteria, restriction enzymes serve as a defense mechanism to protect against invading viruses by cutting up foreign DNA, distinguishing it from the bacterium's own DNA through methylation patterns.

Step-by-step explanation:

The role of restriction enzymes in bacteria is primarily defensive. They function to protect the cell from invading phages by recognizing and cutting up the foreign DNA. This is accomplished through the restriction modification system, which consists of two types of enzymes: DNA methylase that methylates the bacteria's own DNA and restriction endonucleases that cleave unmethylated, foreign DNA.

Because the bacterial DNA is methylated at specific sequences, the restriction enzymes do not cut it, allowing these enzymes to differentiate between foreign and self DNA. This process effectively prevents the propagation of phages and other foreign genetic material within the bacterial cell.

While restriction enzymes are a key tool in modern recombinant DNA technology, their natural function in bacteria is not to facilitate the acceptance of foreign DNA or new phenotypes, but rather to safeguard the integrity of the bacterial genome.