Identify the correct statements regarding EcoRI:
(A) It cuts DNA between A and T when GAATTC palindrome is present in the DNA
(B) It produces blunt ends in the fragments
(C) The blunt ends facilitates the action of the enzyme
(D) It cuts DNA between G and A when GAATTC sequence is present in the DNA
(E) GAATTC is the palindrome recognized by EcoRI
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (D) and (E) Only
(A) It cuts DNA between A and T when GAATTC palindrome is present in the DNA — False. EcoRI cuts between G and A.
(B) It produces blunt ends in the fragments — False. It produces sticky ends.
(C) The blunt ends facilitates the action of the enzyme — False. Sticky ends help DNA ligase join the fragments.
(D) It cuts DNA between G and A when GAATTC sequence is present in the DNA — True.
(E) GAATTC is the palindrome recognized by EcoRI — True.
NCERT Extract:
Restriction Enzymes – “… Restriction enzymes cut the strand of DNA a little away from the centre 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 (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.”