Chapter 8, Problem 5CT

Summary Introduction

To answer:

Recognition and restriction of DNA sequence by HhaI.

Introduction:

Restriction enzymes recognize and cut DNA nucleotide sequences at the specific sites is called restriction site. Most of the restriction sites are palindromic sequences (the sequence can be read both forward or backward). The hundreds of restriction enzymes are classified into two groups based on their types of cuts (sticky or blunt ends) on DNA sequences. EcoRI cuts DNA sequence and both ends have overhanging ssDNA pieces (staggered cut) is called sticky ends. HindII and SmaI cut dsDNA at the same point and produced blunt ends. In bacteria, restriction enzymes are used for their protection from phages, which are cleaved by restriction enzymes into nonfunctional nucleotide pieces. However, bacterial DNAs are protected by methylation mechanism. Restriction enzymes are mostly denoted by three or more letters which indicates their genus and bacterial sources.