Final answer:
DNA replication is the process by which a DNA double helix is unwound by DNA helicase and copied by DNA polymerase to produce two identical daughter DNA molecules. The Meselson and Stahl experiments provided empirical support for the semi-conservative nature of DNA replication. This complex process is essential for cell division and the maintenance of genetic information.
Step-by-step explanation:
DNA replication is a critical process for cellular reproduction, where the original DNA molecule is copied to produce two identical daughter DNA molecules. The structure of DNA - a double helix - facilitates this replication process. During replication, enzymes such as DNA helicase unwind the double helix and DNA polymerase attaches new nucleotides to each original strand, creating two exact copies. This semi-conservative nature ensures that each of the daughter molecules contains one original and one new strand of DNA.
Meselson and Stahl Experiment
The Meselson and Stahl experiments confirmed the semi-conservative mechanism of DNA replication. They grew bacteria in heavy nitrogen (N-15) and then switched it to light nitrogen (N-14) and observed the DNA via centrifugation. Successive generations showed an intermediate band of DNA (indicating one old and one new strand), supporting the semi-conservative replication model.
Overall, the process of DNA replication is a complex interaction of multiple enzymes and occurs in three main steps: initiation, where the double helix is opened; elongation, where new strands are synthesized; and termination, where the replication process concludes and two complete DNA molecules are formed.