S. cerevisiae is also considered to be a "model organism" by scientists. Its big advantage is that it is both a unicellular and eukaryotic organism. As a eukaryote, a majority of the yeast genes and proteins have human homologs (12), and a greater understanding of the yeast genome would also help scientists understand the human genome. Another advantage is its fast growth grate. On a normal yeast medium, it takes 90 minutes for the yeast population to double. (13), and colonies are usually visible 2-3 days after placing them on fresh medium. Since the complete genome sequence is now available, mutants unique to eukaryotic organisms can now be expressed in an eukaryote as opposed to studying a similar gene in prokaryotes.