Question

Each restriction enzyme cleaves a molecule only at

• A. methyl groups
• B. the ends of genes
• C. the time of DNA replication
• D. a particular nucleotide sequence

Answer 1

The correct option is D a particular nucleotide sequence

A restriction enzyme is an enzyme that belongs to a larger group of an enzyme called nucleases and recognizes a specific nucleotide sequence and cuts the DNA only at a specific site which is known as the restriction site. There are two types of nucleases - exonucleases and endonuclease. Exonucleases remove nucleotides from the ends of the DNA, whereas endonuclease makes cuts at specific positions within the DNA.

So the correct option is 'a particular nucleotide sequence'.