Compare conservative, semiconservative, and dispersive modes of DNA replication.

Verified step by step guidance

1. Understand that DNA replication is the process by which a DNA molecule makes a copy of itself, and there are three proposed models for how this replication could occur: conservative, semiconservative, and dispersive.
2. In the conservative model, the original DNA molecule remains intact, and an entirely new copy is made. This means after replication, one molecule is the original and the other is completely new.
3. In the semiconservative model, each of the two strands of the original DNA molecule serves as a template for a new strand. After replication, each DNA molecule consists of one original strand and one new strand.
4. In the dispersive model, the original DNA molecule is broken into pieces, and new DNA is synthesized in short segments. After replication, each DNA molecule is a mix of old and new DNA segments.
5. Reflect on the experimental evidence, such as the Meselson-Stahl experiment, which supported the semiconservative model by showing that DNA replication results in molecules with one old and one new strand.

Key Concepts

Conservative Replication

In conservative replication, the original DNA molecule remains intact, while an entirely new copy is synthesized. This means that after replication, one double helix consists of both original strands, and the other consists of two newly synthesized strands. This model was proposed to explain how genetic information is preserved, but experimental evidence has shown it does not accurately describe DNA replication.

Semiconservative Replication

Semiconservative replication is the widely accepted model of DNA replication, where each of the two resulting DNA molecules consists of one original strand and one newly synthesized strand. This method ensures that genetic information is accurately passed on during cell division, as each daughter cell receives one strand from the parent DNA and one newly formed strand, maintaining the integrity of the genetic code.

Dispersive Replication

Dispersive replication suggests that the parental DNA strands are broken into pieces, and both the new and old DNA are interspersed in the daughter molecules. This model implies that the resulting DNA strands would be a mosaic of old and new DNA. However, like conservative replication, this model lacks strong experimental support and is less favored compared to the semiconservative model.