Suppose a team of researchers sequences the genome and measures the proteome of a human skin cell and a human kidney cell. Will there be a greater difference between the genome or the proteome between these two cells? The genome is more different between the cells than the proteome because gene expression varies between the two cells. The proteome is the genetic material in a prokaryotic cell, and thus these cells do not have a proteome because they are eukaryotic. There is no difference in the variability between the genome and proteome of the two cells because a gene codes for a single protein. The genome is more different between the two cells than the proteome due to the variety of molecules associated with DNA, including histones, regulatory proteins, and enzymes. The proteome is more different between the cells due to differences in gene expression and post-transcriptional processing of mRNA.