Question

Which of the following enzymes cut the DNA molecule at specific nucleotide sequence?

• A. Restriction endonuclease
• B. DNA ligase
• C. RNA polymerase
• D. Exonuclease

Answer 1

The correct option is A Restriction endonuclease

Restriction endonucleases recognise specific sequences in the DNA and cut the DNA into fragments. The specific sites are 4-6 bp long and are called as restriction sites. Each restriction endonuclease has a specific restriction site. Ligase enzyme joins two large molecules by forming a new chemical bond, e.g., DNA ligase joins two DNA fragments together via phosphodiester bond between two nucleotides. Exonucleases enzymes remove nucleotides one at a time from the end of a polynucleotide chain. They shorten the DNA by one nucleotide at a time, they do not digest it into fragments. RNA polymerase is a DNA-dependent RNA polymerase that copies the template DNA strand into primary transcript RNA through transcription. It extends the primer into RNA transcript, does not cut the DNA.

So, the correct answer is option A.