Final answer:
DNA replication is semiconservative, with each strand of the double helix acting as a template for a new strand. The leading strand is synthesized continuously, while the lagging strand is made up of Okazaki fragments that are later connected.
Step-by-step explanation:
Understanding DNA Replication
During the process of DNA replication, each of the two strands of the DNA double helix serves as a template for the formation of a new complementary strand. This process is known as semiconservative replication, as one 'parental' or original strand is conserved in each new DNA molecule. In humans and other eukaryotes, the DNA replication begins at a single origin of replication, where the DNA unwinds to form a replication fork.
The replication mechanism involves the synthesis of one strand continuously towards the replication fork. This is known as the leading strand, as it can be synthesized in a smooth, continuous way from the 5' to the 3' end. In contrast, the other strand, known as the lagging strand, is synthesized discontinuously in the opposite direction, creating short segments called Okazaki fragments. These fragments are later joined together by the enzyme DNA ligase to form a complete strand.
When only one strand of DNA is damaged, the cell utilizes various excision repair mechanisms. These mechanisms remove the damaged nucleotides and fill in the gaps with correct ones, using the undamaged complementary strand as a guide. This ensures the high fidelity of DNA replication and repair, preserving genetic information across generations.