Hint: Restriction enzymes are DNA-cutting enzymes. They are found in bacteria.
A restriction enzyme works accordingly using shape to shape matching. When it encounters 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.
Hence, option B: Double-stranded DNA, is the correct answer.
- Restriction enzymes, restriction endonucleases are found in bacteria and other prokaryotes. - They identify and bind to specific sequences of DNA, known to be restriction sites. An individual restriction enzyme recognizes one or few restriction sites, as it finds its target sequence, a restriction enzyme makes a double-stranded cut in the DNA molecule.
- Generally, the cut is near or at the restriction site and occurs in a precise and predictable pattern.
- Restriction enzymes hydrolyze covalent phosphodiester bonds of the DNA to leave either cohesive ends or blunt ends.
- The variation in the cut is important because a sticky end can be used to match up a piece of DNA cut with the same enzyme to bind them back together.
- Restriction enzymes always cut Double-stranded DNA in a very specific pattern that produces ends with single-stranded DNA overhangs.
- But not all restriction enzymes produce cohesive ends. Some are known as blunt cutters as they cut straight down the middle of a target sequence and leave no overhang.
Note: Restriction enzymes and DNA ligase are often used to insert genes and other pieces of DNA into plasmids during DNA cloning.