# What is a biological function of restriction enzyme?

Mar 18, 2018

#### Answer:

To restrict foreign DNA

#### Explanation:

Restriction enzymes act like a primitive immune system for some bacteria. They recognize a palindromic sequence of DNA (one that reads the same forward and backward.....like the name HANNAH) and the cut this sequence.

Generally the target sequence they cut is in low abundance in their own genomes, and so when a bacteriophage or different bacteria tries to invade them, the restriction enzymes will target the sequence and cut the DNA in an attempt to slow down or kill the invader.

We use restriction enzymes in molecular biology because they are so good at cutting DNA at a specific site. Most restriction enzyme recognition sites are 6 nucleotides long, so you'd expect to find the restriction enyzme site once in every ${4}^{6}$ basepairs, or once every 4096 basepairs.