Match the LIST-I with LIST-II
| LIST-I | LIST-II |
|---|---|
| Enzymes | Features |
| A. EcoR I | I. Remove nucleotides from ends of DNA |
| B. Hind II | II. Joins DNA fragments |
| C. DNA ligase | III. First restriction endonuclease |
| D. Exonuclease | IV. Produce sticky ends |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A-IV, B-III, C-II, D-I
(A) EcoR I — this matches (IV) Produce sticky ends. It is a restriction endonuclease that cuts the two strands of DNA a little apart, at a palindromic site. This leaves short single-stranded overhangs, called sticky ends, which can pair with complementary ends.
(B) Hind II — this matches (III) First restriction endonuclease. It was the first restriction endonuclease to be isolated. It always cuts DNA at a particular point by recognising a specific sequence of six base pairs.
(C) DNA ligase — this matches (II) Joins DNA fragments. It acts on cut DNA molecules and joins their ends, which gives recombinant DNA.
(D) Exonuclease — this matches (I) Remove nucleotides from ends of DNA. Exonucleases remove nucleotides from the ends of DNA. Endonucleases, in contrast, cut at specific positions inside the DNA.
NCERT Extract:
Restriction Enzymes – “… Restriction enzymes belong to a larger class of enzymes called nucleases. These are of two kinds; exonucleases and endonucleases. Exonucleases remove nucleotides from the ends of the DNA whereas, endonucleases make cuts at specific positions within the DNA.”
Restriction Enzymes – “… This leaves single stranded portions at the ends. There are overhanging stretches called sticky ends on each strand (Figure 9.1). These are named so because they form hydrogen bonds with their complementary cut counterparts. This stickiness of the ends facilitates the action of the enzyme DNA ligase.”
