Question

DNA ligase is mainly used in biotechnology because it:

• A. Cuts DNA at specific sites
• B. Joins DNA fragments together
• C. Synthesizes RNA molecules
• D. Breaks hydrogen bonds

Hint:

Remember: \[ \text{Restriction enzyme} \rightarrow \text{Cuts DNA} \] \[ \text{DNA ligase} \rightarrow \text{Joins DNA} \]

Answer 1

The Correct Option is B

Concept: DNA ligase acts as a molecular glue in recombinant DNA technology.

Step 1: Understand function of DNA ligase. DNA ligase:

• Joins DNA fragments
• Forms phosphodiester bonds
• Helps produce recombinant DNA

Step 2: Eliminate incorrect options.

• Restriction enzymes cut DNA
• RNA polymerase synthesizes RNA
• Helicase breaks hydrogen bonds

Therefore, the correct answer is: \[ \boxed{\text{Joins DNA fragments together}} \]