Question

In which direction does the replication fork move?

a. it moves ahead of the newly synthesized DNA
b. it moves ahead of the unzipped DNA
c. it moves from the double-stranded to the single-stranded DNA
d. it moves towards the stabilizing proteins

Answer 1

The replication fork moves in the direction that allows the DNA polymerase to add nucleotides in the 5' to 3' direction. The leading strand synthesis moves towards the fork, while the lagging strand is synthesized away from the fork in short stretches known as Okazaki fragments.

Step-by-step explanation:

The replication fork moves in a defined direction during DNA replication. Primarily, the synthesis of the new DNA occurs with the help of DNA polymerase, which can only add nucleotides in the 5' to 3' direction. This means that while one strand, the leading strand, can be synthesized continuously towards the replication fork, the opposite strand, known as the lagging strand, must be replicated in a discontinuous manner.

The lagging strand is synthesized away from the replication fork, in short stretches of DNA called Okazaki fragments. This process requires multiple priming events, as each new fragment begins with an RNA primer. The directionality of replication is integral to the fidelity and efficiency of DNA synthesis, a process that occurs at a remarkable rate of 1000 nucleotides per second.

In conclusion, the leading strand replicates continuously towards the replication fork, and the lagging strand is synthesized away from it in a discontinuous fashion, demonstrating the antiparallel nature of DNA strands and the enzymatic constraints of DNA polymerase.