Identify the wrong statement with regard to Restriction Enzymes
- Sticky ends can be joined by using DNA ligases.
- They cut the strand of DNA at palindromic sites.
- Each restriction enzyme functions by inspecting the length of a DNA sequence.
- They are useful in genetic engineering
Answer
(3) Each restriction enzyme functions by inspecting the length of a DNA sequence.
Solution
(1) Correct – restriction endonucleases leave sticky ends, which are joined together by DNA ligases.
(2) Correct – each restriction endonuclease recognises a specific palindromic nucleotide sequence and cuts the DNA strands there.
(3) Wrong – as per NCERT, the enzyme 'inspects' the DNA only to find its specific recognition sequence; its action depends on that base sequence (e.g. EcoRI: GAATTC), not on the length of DNA.
(4) Correct – they are the 'molecular scissors' of genetic engineering.
Answer: (3)