Question

What is restriction endonuclease? Give any two examples.

Hint:

Restriction enzymes are called molecular scissors. EcoRI and HindIII are common examples used in biotechnology.

Answer 1

Definition: Restriction endonucleases are enzymes that cut DNA molecules at specific recognition sequences. They are also called molecular scissors and are essential tools in recombinant DNA technology. Key Features: \[\begin{array}{rl} \bullet & \text{Recognize specific short DNA sequences (usually palindromic sequences).} \\ \bullet & \text{Cut DNA at these sites, producing either sticky ends (overhanging ends) or blunt ends.} \\ \bullet & \text{Widely used in gene cloning, DNA mapping, and genetic engineering.} \\ \end{array}\] Examples: \begin{enumerate} \item EcoRI: Cuts DNA at the sequence \texttt{GAATTC} between G and A, producing sticky ends. \item HindIII: Cuts DNA at the sequence \texttt{AAGCTT}, also producing sticky ends. \end{enumerate} Conclusion: Restriction enzymes revolutionized molecular biology by enabling scientists to cut and manipulate DNA precisely.