Question

Which of the following differences are incorrect between leading and lagging strands of DNA?

	Leading strand	Lagging strand
(i)	It does not require DNA ligase for its growth	DNA ligase is required for joining Okazaki
(ii)	Formation of leading strand is slower	Formation of lagging strand is quite rapid.
(iii)	Its template opens in in 5 // 3 direction	Its template opens in 3 // 5 direction.
(iv)	Formation of leading strand begins immediately at the beginning of replication.	Formation of lagging strand begins a bit later than that of leading strand

• A. (ii) and (iv) only
• B. (ii), (iii) and (iv) only
• C. (ii) and (iii) only
• D. (i), (ii) and (iii) only

Answer 1

The correct option is C (ii) and (iii) only

The synthesis of the leading strand is more rapid compared to the lagging strand synthesis as it happens at a stretch and does not involve the formation of small segments of DNA to be joined by DNA ligase. Also the template for both the strands open from the same direction which is the 3' to 5' direction and the synthesis happens in the 5' to 3' direction

So, the correct option is '(ii) and (iii) only'.