Question

1. the Meselson-Stahl experiments and this paper are consider important, groundbreaking studies in molecular biology. Some of the clarity of the centrifugation result was due to the fact the DNA was fragmented during handling. When DNA break into fragment, the sugar phosphate backbone is broken forming many short double helices. Why did the fragmented DNA still show the pattern of nitrgogen density banding?

2. which component of a DNA nucleotide contains nitrogen?

3. what would happen in the distribution of the parental atoms into daughter molecules if DNA replication followed a "conservative" model?