(iv) yeast genetic system has been very thoroughly understood where about 600 genes are already mapped, although they may still represent a fraction of the whole genome;
(v) DNA molecules as long as 100kb can be routinely handled through PFGE. These can be produced by enzymes like Dpn I or Not I, which recognize rare sites.
 Yeast cell has 16 chromosomes, each with a single DNA molecule. Until recently, even the smallest of these DNA molecules was too large to be isolated in pure form, but due to the recent availability of pulsed field gel electrophoresis (PFGE), where short pulses of electricity are used in two different directions, separation of DNA belonging lo each of the 16 individual chromosomes has become possible.

These agarose plugs are subjected to PFGE or CHEF gel electrophoresis, which yields 15 bands for 16 chromosomes in case of yeast, 6 bands for 8 chromosomes in Aspergillus nidulans, and 7 bands for 7 chromosomes in D. discoideum. In case of yeast, initally chromosome 12 did not clearly separate.
Another strain of yeast (YPH 149) allowed identification of each of the 16 chromosomes as 17 distinct bands using alternating CHEF gel electrophoresis (chromosome VII split into two). In Aspergillus, 2 of the 6 bands are doublets with 3.8 Mbp and 3.5 Mbp respectively. Thus these bands are in agreement with genetic and cytological information available in these cases.
The details of different DNA bands in yeast and Aspergillus nidulans along with the linkage groups to which these bands belong. The sizes of bands are measured by comparing with bands of known sizes obtained from agarose plugs having yeast intact chromosomes, The bands are assigned to specific linkage groups by using one of the several possible methods.