Chapter 12, Problem 11PS

Interpreting Data When comparing genomes from different species, biologists often calculate the genome density, the number of genes per number of nucleotides in the genome. Refer to Figure 12.20. You can estimate the gene density of each species by dividing the number of genes by the size of the genome (usually expressed in Mb, which is mega base pairs, or 1 million base pairs). Using a spreadsheet, estimate the gene density for every species in the figure. (Don’t forget that 1 billion = 1,000 million; for example, humans have 3,000 Mb.) How does the gene density of bacteria compare to humans? Humans and roundworms have nearly the same number of genes, but how do the gene densities of these two species compare? Can you identify any general correlation between gene density and the size or complexity of an organism?