Question

What is restriction endonuclease? Give any two examples.

Hint:

Restriction enzymes are essential for cutting and manipulating DNA, allowing researchers to study genes and produce recombinant organisms.

Answer 1

Step 1: Definition of Restriction Endonuclease.
Restriction endonucleases, also known as restriction enzymes, are enzymes that cut DNA molecules at specific nucleotide sequences. They act as molecular scissors and are naturally found in bacteria, where they protect against viral DNA by cutting it into smaller pieces.
Step 2: Function of Restriction Enzymes.
These enzymes recognize specific sequences of nucleotides (restriction sites) in DNA and cut the DNA at or near these sites. Restriction enzymes are critical tools in molecular biology, particularly in cloning, DNA mapping, and recombinant DNA technology.
Step 3: Examples of Restriction Enzymes.
1. EcoRI: It recognizes the sequence GAATTC and cuts between G and A. 2. HindIII: It recognizes the sequence AAGCTT and cuts between the two A's.
Final Answer: \[ \boxed{\text{Restriction endonucleases are enzymes that cut DNA at specific sequences. Examples: EcoRI, HindIII.}} \]