Table 1.

N Content of Genetic Informational Molecules

Species	Genome		Transcriptome				Proteome
	No. of Bases	N Content	No. of Genes	No. of Bases	N Content		No. of Proteins	No. of Residues	N Content
					Mean	SD			Mean	SD
Arabidopsis thaliana	119 × 106	3.680**	26,544	24 × 106	3.485**	0.113	31,921	13 × 106	0.364**	0.079
Drosophila melanogaster	128 × 106	3.711	18,042	113 × 106	3.643	0.101	20,736	11 × 106	0.386	0.085
Homo sapiens	2.8 × 109	3.704	25,022	1.5 × 109	3.701	0.076	25,305	14 × 106	0.377	0.078

NOTE.—N content is the number of N atoms per monomer. The number of genes is lower than the number of proteins because genes without introns cannot be used for transcriptome analyses. Only experimentally validated isoforms were included for each gene. Standard deviations (SD) are shown, wherever appropriate, because the standard errors are close to zero due to very large sample sizes.

^**Cases where the observed differences between the plant and animal genomes were significant at P « 0.01 in Student's t-test or the Fisher's exact test.