Replication of DNA (Scottish Higher)

In vivo

DNA Replication Theories

DNA Replication

In vitro

Controls and Applications

Visualising DNA with Gel Electrophoresis

DNA Profiling



In vivo

DNA replication is carried out spontaneously in living organisms (in vivo).

DNA, of course, replicates. Why? It’s a pretty crucial element in the reproduction of living things. For example, a bacterium replicates by splitting itself into 2 (binary fission). The DNA must stay intact and be copied with a high degree of accuracy in order for the two newly formed bacteria to develop and function as their parent – adequately. In multi-cellular organisms such as ourselves, DNA replication occurs as a prelude to cell division.

For such a complex molecule, past scientists have had a challenging time working out the precise mechanism by which DNA replicates.

  • Three hypotheses were made: (for this purpose imagine one DNA molecule)

1. The DNA molecule replicates by providing itself as a template for a brand new shiny DNA molecule, and then remaining its own intact DNA molecule. This is called the conservative replication model.

2. The DNA molecule replicates by providing itself as a template and being modified itself throughout, resulting in 2 new DNA molecules with patches of the old parent DNA molecule combined with patches of brand new material. This is called the dispersive replication model.

3. The DNA molecule replicates by providing each of its strands as a template for 2 new DNA molecules, each having one entire new strand, and one entire old strand from the parent DNA molecule. This is called…