Question

The cutting of DNA at specific locations became possible with the discovery of -

• A. Reverse transcriptase
• B. Restriction endonuclease
• C. Bacteriophage
• D. P. C. R.

Hint:

Remember the key tools of genetic engineering and their functions: {Cutting DNA:} Restriction Endonucleases {Pasting DNA:} DNA Ligase {Copying DNA:} DNA Polymerase (used in PCR) {Making DNA from RNA:} Reverse Transcriptase

Answer 1

The Correct Option is B

Step 1: Concept Overview:
The question concerns the discovery that allowed scientists to cut DNA at specific, predictable locations, which is fundamental to genetic engineering.
Step 2: Detailed Explanations:
Reverse transcriptase: This enzyme creates DNA from an RNA template, producing cDNA but not cutting DNA.
Restriction endonuclease: Also called a restriction enzyme, this protein identifies a specific short DNA sequence (the restriction site) and cuts the DNA at or near that site. This discovery enabled precise DNA cutting and joining, initiating recombinant DNA technology; they function as "molecular scissors."
Bacteriophage: A virus infecting bacteria. While phages can provide useful enzymes or serve as cloning vectors, the phage itself doesn't cut DNA.
P. C. R. (Polymerase Chain Reaction): This technique amplifies a particular DNA segment, generating numerous copies. It synthesizes DNA, rather than cutting it.
Step 3: Conclusion:
The discovery of restriction endonucleases enabled the specific cutting of DNA.