Question

The lagging strand is synthesized __________ , while the leading strand can be synthesized __________. continuously; discontinuously discontinuously; continuously 5'-to-3'; 3'-to-5' 3'-to-5'; 5'-to-3' quickly; slowly

Answer 1

Answer: The correct answer for the blank is- discontinuously and continuously.

Leading and lagging strands are the two newly synthesized strands in the process of DNA replication ( formation of two identical DNA copies from an original DNA).

During DNA replication, two strands of original DNA are first separated (with the help of enzyme helicase) so that template DNA is exposed.

The strand with 3' to 5' direction acts as a template for leading strand and DNA is synthesized in a continuous manner ( as it runs in the direction of movement of replication fork) in the direction 5' to 3'.

On the other hand, the DNA with 5' to 3' direction, acts as a template for lagging strand and DNA is synthesized in a discontinuous manner because in this case, enzyme DNA polymerase has to wait for the 3' end to be exposed ( as for the DNA synthesis, it has to move in the opposite direction of the replication folk) so as to make the DNA in the direction 5' to 3'.