How does semiconservative relates to DNA replication?
Semiconservative refers to a specific model of DNA replication. In this model, each newly formed DNA molecule contains one strand that is original (parental) and one strand that is newly synthesized (daughter). This concept was initially proposed by Watson and Crick, who described DNA replication as a process where the double helix unwinds and each strand serves as a template for the synthesis of a new complementary strand.
To understand how semiconservative replication works, here is a step-by-step explanation:
1. DNA replication initiates at specific sites along the DNA molecule called origins of replication.
2. An enzyme called DNA helicase unwinds and separates the two strands of DNA, forming a replication fork.
3. Another enzyme called DNA polymerase adds nucleotides to the growing DNA strand in a step-by-step manner. It can only add nucleotides in the 5' to 3' direction.
4. DNA polymerase synthesizes the new strand by pairing complementary nucleotides to the template strand. Adenine (A) bonds with thymine (T), and guanine (G) bonds with cytosine (C).
5. As the two parental DNA strands are separated, each strand serves as a template for the synthesis of a new complementary strand. One new strand is synthesized continuously (leading strand) because it aligns with the replication fork's direction. The other new strand is synthesized discontinuously in short fragments (lagging strand) called Okazaki fragments, which are later joined together.
6. After completing the replication process for both strands, each resulting DNA molecule consists of one original (parental) strand and one newly synthesized (daughter) strand. Hence, this type of replication is termed semiconservative because one part of the DNA molecule is conserved, and the other is newly synthesized.
The principle of semiconservative replication is significant as it ensures that genetic information is accurately passed from one generation to the next. It also allows for error correction mechanisms to fix mistakes during DNA replication, contributing to the overall stability and fidelity of the DNA replication process.