Question

(b) “DNA replication is continuous and discontinuous on the two strands within the replication fork.” Explain with the help of a schematic representation.

Hint:

Remember, the key difference lies in the directionality of synthesis: the leading strand is synthesized in one continuous stretch, while the lagging strand involves multiple short fragments.

Answer 1

DNA replication occurs in a semi-conservative manner, where the parental DNA strands serve as templates for the synthesis of new complementary strands. Due to the antiparallel nature of DNA and the unidirectional activity of DNA polymerase (5' to 3'), the two strands at the replication fork are synthesized differently: \begin{itemize} \item Leading strand: Synthesized continuously in the 5' to 3' direction, as it follows the replication fork movement. \item Lagging strand: Synthesized discontinuously in small fragments called Okazaki fragments, which are later joined by DNA ligase. \end{itemize} Schematic Representation: \begin{figure}[H] \centering \includegraphics[width=0.7\linewidth]{Screenshot 2025-01-23 090112.png} % Replace 'path_to_image.png' with the actual schematic representation file path \caption{Schematic diagram of DNA replication showing the continuous synthesis of the leading strand and the discontinuous synthesis of the lagging strand with Okazaki fragments.} \label{fig:dna_replication} \end{figure} % Quick tip