NEETZoologyBiotechnology - Principles and Processes
A researcher isolates a linear double-stranded DNA fragment that possesses short, single-stranded overhanging stretches at both of its ends. Which of the following statements correctly describes the enzyme responsible for generating this specific type of DNA fragment?
Options
- AIt is an exonuclease that removed nucleotides from the terminal ends of the DNA.
- BIt is a restriction endonuclease that cut the DNA strands a little away from the centre of the palindromic sit
- CIt is a restriction endonuclease that cut both DNA strands exactly at the centre of the palindromic site.
- DIt is a DNA ligase that failed to fully join the complementary strands.
Correct answer
B. It is a restriction endonuclease that cut the DNA strands a little away from the centre of the palindromic sit
Step-by-step solution
The single-stranded overhanging stretches at the ends of the DNA fragment are known as 'sticky ends'. Sticky ends are produced by restriction endonucleases when they cut the DNA strands a little away from the centre of the palindromic recognition site, but between the same two bases on opposite strands. Exonucleases remove nucleotides from the ends but do not specifically generate these palindromic sticky ends. Endonucleases that cut exactly at the centre of the palindromic site produce blunt ends, not sticky ends.