A proposal for the structure of the Drosophila genome.

We propose a structure for the genome of Drosophila melanogaster in which each chromatid of each chromomere (band) consists on the average of about 30-35 different sequences of single-copy (unique) DNA, each on the average about 750 base pairs in length. These are separated from one another by stretches of the middle repetitive (reiterated) DNA, which in D. melanogaster makes up about 15% of the genome. These stretches are about 100-150 base pairs in length and are all of the same sequence or family in each individual chromomere and of a different family (sequence) in each different chromomere. Our proposed structure of the Drosophila genome is in accord with all of the known facts concerning the physical chemistry and molecular biology of Drosophila DNA.