As I was reading Griffith's Introduction to genetic analysis this evidence was provided for single DNA makes single chromosome.
Eventually geneticists demonstrated directly that certain chromosomes contain single DNA molecules. One strategy was to use pulsed field gel electrophoresis, a specialized electrophoretic technique for separating very long DNA molecules by size. The extracted DNA of an organism with relatively small chromosomes, such as the fungus Neurospora, is subjected to electrophoresis for long periods of time in this apparatus. The number of bands that appear on the gel is equal to the number of chromosomes (seven, for Neurospora).
This points to the fact that one chromosome has single DNA. What I want to know is that what evidence is there that each chromosome is not made up of multiple similar sized DNA molecules all coiled together to give a single chromosome so that the number of different types of DNA molecules to number of chromosomes have ratio one to one but one type of DNA molecule's multiple copies makes one chromosome.