1. The diagram below represents a stage in the process of DNA replication - Scottish Highers Human Biology - Question 1 - 2016

The chemical group found at the 5′ end of a DNA strand is a phosphate group.

Strand B is replicated continuously because it is oriented in the 5′ to 3′ direction, allowing DNA polymerase to add nucleotides smoothly. In contrast, strand A is replicated in fragments because it runs in the opposite direction (3′ to 5′), requiring short segments called Okazaki fragments to be synthesized separately.

DNA polymerase adds nucleotides to the new strand or primer during DNA replication, ensuring that the complementary bases pair correctly.

Ligase joins fragments of DNA, particularly the Okazaki fragments on the lagging strand, by forming phosphodiester bonds to create a continuous strand.