Question: what is the difference between bacterial chromosomal dna and plasmid dna preparation?
Answer: Because plasmids are small, they can easily reanneal forming dsDNA. Genomic DNA, however, is too long to reanneal fully, and instead it tends to tangle so that complimentary strands remain separated. During centrifugation, gDNA (bound to protein) forms a pellet while plasmid DNA remains soluble.