The first attempt to annotate the human genome (interpret the sequence in terms of the numbers and types of genes it coded ) -- human genome contains about 30,000 protein-coding genes. Difference in complexity of organisms cannot be explained by the number of protein- coding genes in their genome. A large portion of genome is transformed into rna with gene regulatory functions. Difference in numbers of elements that make up the protein network. Comparative genomics: if it"s conserved, it must be important . The majority of the genome consists of dna has resides between the gene, they. Each of roughly 21000 human genes consist largely of non coding portions intronic represent intergenic dna. Indicate that only a small protein coding portion in dna. The other sections for encoding are subject to natural selection. Some have regulatory functions while others have chromosomal functions . E. g. similarities between human and mouse genome.