Which of the following statements are correct about restriction enzymes?
(A). Each restriction endonuclease recognizes a specific palindromic nucleotide sequence in the DNA.
(B). Endonuclease removes nucleotides from the terminal end of the DNA.
(C). The first discovered restriction endonuclease is Hind II.
(D). Restriction enzymes belong to a larger class of enzyme polymerase.
Choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A) and (C) only
(A) Each restriction endonuclease recognizes a specific palindromic nucleotide sequence in the DNA. Correct. A palindrome in DNA is a sequence of base pairs that reads the same on the two strands when both are read in the same direction. Each restriction enzyme cuts only at its own such sequence.
(B) Endonuclease removes nucleotides from the terminal end of the DNA. Incorrect. Removing nucleotides from the ends is the work of exonucleases. Endonucleases cut inside the DNA.
(C) The first discovered restriction endonuclease is Hind II. Correct. Hind II was the first restriction endonuclease to be isolated and characterised. It always cuts DNA at a point where it finds a particular sequence of six base pairs.
(D) Restriction enzymes belong to a larger class of enzyme polymerase. Incorrect. Restriction enzymes belong to the nucleases. Polymerases do the opposite job: they join nucleotides to build DNA or RNA.
NCERT Extract:
Restriction Enzymes – …
