Question

A biotechnologist was given two restriction endonucleases (RE-A and RE-B) with the following restriction sites:

After the action of respective endonucleases, the fragments separated from the restriction sites. Draw the separated fragments on both the sites.

Answer 1

Restriction Enzyme A (RE-A)

RE-A cuts the DNA sequence symmetrically at the center of the recognition site. This produces Blunt Ends (no overhanging bases).

• Original Sequence:
  
  5′ G ↓ A A T T C 3′
  5′ G ↓ A A T T C 3′
• Separated Fragments:

(The AATT sequence on both fragments forms the “sticky” overhangs.)

Enzyme	Type of Cut	Type of Ends Produced
RE-A	Symmetrical (at the center)	Blunt Ends
RE-B	Asymmetrical (away from center)	Sticky Ends