The Proof That Eukaryotic Chromosomal Replication was a Semi-Conservative Process

Question

The proof that eukaryotic chromosomal replication was a semi-conservative process:
A) Used ³H-thymidine to label E. coli DNA.
B) Used ³H-thymidine to label human cell DNA.
C) Relied on the assumption that each chromosome in the broad bean consisted of a single DNA molecule.
D) Did not require the fact that each chromosome consists of a single strand of DNA.
E) None of these

Accepted Answer

The Meselson-Stahl experiment, which provided the proof that eukaryotic chromosomal replication was a semi-conservative process, used broad bean chromosomes that were assumed to consist of a single DNA molecule. Meselson and Stahl grew the broad beans in a medium containing 15N for many generations, leading to the heavy isotope's incorporation into the DNA. They shifted the plants to a medium containing 14N for one generation and extracted the DNA to analyze its density gradient. They observed that the DNA formed two bands, indicating that it consisted of both light and heavy strands, supporting the semi-conservative model of DNA replication.