Question

What is the recognition site for a restriction enzyme?

Answer 1

Restriction enzyme:

1. A restriction enzyme is a bacterial protein that cleaves DNA sequences at sequence-specific places, resulting in DNA fragments having a known sequence at either end.
2. Restriction enzymes are enzymes generated by certain bacteria that cleave DNA molecules at or near particular base sequences.
3. Bacteriophages are protected from living bacteria by restriction enzymes.

Types of restriction enzymes include:

1. Type I: These remove the DNA from the recognition sequences.
2. Type II: These cuts are made at selected locations near or within the restricted sites.
3. Type III: These are multifunctional proteins composed of two subunits: Res and Mod.

Recognition site for a restriction enzyme:

1. The recognition site or recognition sequence is the unique sequence of bases that defines the restriction enzyme's cleavage site.
2. When a restriction enzyme detects a DNA sequence, it hydrolyzes the link between neighbouring nucleotides, causing the DNA molecule to cleave.
3. Recognition sites are dispersed at random across the DNA.
4. Hind III restriction enzyme recognizes A^AGCTT sites and produces sticky ends.
5. Pst I cleave DNA at the recognition sequence 5′-CTGCA/G-3′ resulting in sticky ends.
6. The cleavage site for the restriction endonuclease EcoRV is 5'-GAT/ATC-3' and produces blunt ends.