AP BIOLOGY

Detailed explanation-1: -Each restriction enzyme recognizes a short, specific sequence of nucleotide bases (the four basic chemical subunits of the linear double-stranded DNA molecule-adenine, cytosine, thymine, and guanine). These regions are called recognition sequences, or recognition sites, and are randomly distributed throughout the DNA.

Detailed explanation-2: -Like all enzymes, a restriction enzyme works by shape-to-shape matching. When it comes into contact with a DNA sequence with a shape that matches a part of the enzyme, called the recognition site, it wraps around the DNA and causes a break in both strands of the DNA molecule.

Detailed explanation-3: -Most restriction enzymes recognize sequences of four to eight base pairs and hydrolyze a single phosphodiester bond on each strand. A characteristic of many of these cleavage or restriction sites is their double rotational symmetry. Generally, the cleavage sites are symmetrically positioned, or palindromic.

Detailed explanation-4: -Many restriction enzymes make staggered cuts at or near their recognition sites, producing ends with a single-stranded overhang. If two DNA molecules have matching ends, they can be joined by the enzyme DNA ligase. DNA ligase seals the gap between the molecules, forming a single piece of DNA.