Question

Restriction endonucleases are used in genetic engineering because

• A. They can degrade harmful proteins.
• B. They can join DNA fragments.
• C. They can cut DNA at variable site.
• D. They can cut DNA at specific base sequences.

Answer 1

The correct option is D They can cut DNA at specific base sequences.

Restriction endonucleases recognize specific sequences in the DNA and cut the DNA into fragments at that site, not at variable sites. The specific sites are 4-6 bp long and are called as restriction sites. Each restriction endonuclease has a specific restriction site. DNA Ligase enzyme joins two DNA fragments together via phosphodiester bond between two nucleotides. Harmful proteins are degraded by proteasomes that are protein complexes present in all eukaryotes and archaea, and in some bacteria. They degrade unneeded or damaged proteins by breaking peptide bonds.