Question

The word "restriction" in the name restriction endonuclease refers to

• A. cutting of DNA at specific palindromic nucleotide sequences
• B. immunity against bacteriophage infections
• C. breaking of phosphodiester bonds
• D. restricting the growth of microorganisms within the host

Answer 1

The correct option is B immunity against bacteriophage infections

The term restriction in restriction endonucleases signifies that it protects the bacteria against bacteriophage infections. Restriction enzymes were named for their ability to restrict, or limit, the number of strains of bacteriophage that can infect a bacterium.

Restriction endonucleases are naturally present in the bacteria where they recognize specific nucleotide sequences in a DNA molecule, often a palindrome known as restriction site, and cleaves the DNA by breaking the phosphodiester bond at a specific nucleotide with the restriction site.