Read the following passage carefully.
Restriction enzyme
Restriction enzymes cut the strand of DNA a little away from the center of the palindrome sites, but between the same two bases on the opposite strands. This leaves single stranded portions at the ends. There are overhanging stretches called sticky ends on each strand. 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. The word palindromes refer to group of letters that forms the same words when read both forward and backward. Restriction endonucleases are used in genetic engineering as molecular scissors.
Overhanging stretches on each strand is called:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Sticky end
Restriction enzymes cut the two strands a little away from the centre of the palindrome. This leaves single-stranded overhanging stretches at each end. They are called sticky ends because they pair with complementary cut ends.
Option (1) Hydrogen bond — Incorrect. The hydrogen bond is the bond the sticky ends form, not the name of the overhang.
Option (2) Sticky end — Correct. The passage calls the overhanging stretches on each strand sticky ends.
Option (3) Ligase — Incorrect. Ligase is the enzyme that seals the joined ends.
Option (4) Palindrome — Incorrect. The palindrome is the recognition sequence where the enzyme cuts, not the overhang left after the cut.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.