Chapter 5: Genomics, Proteomics, & Systems Biology

Genomics, Proteomics, & Systems Biology begins by detailing the history and progression of genome sequencing, starting with simple organisms like the bacterium Haemophilus influenzae and the yeast Saccharomyces cerevisiae, and advancing to multicellular models such as Caenorhabditis elegans, Drosophila melanogaster, and Arabidopsis thaliana. The text highlights the major achievements of the Human Genome Project and the surprising discovery that the human genome contains only about 20,000 protein-coding genes—representing roughly one percent of the total DNA—which implies that biological complexity arises largely from non-coding regulatory sequences and alternative splicing rather than gene count. The discussion includes the technological evolution from dideoxynucleotide sequencing to next-generation sequencing (massively parallel sequencing), which has enabled affordable personal genomics and rapid whole-genome analysis. The chapter also explores the transcriptome, explaining how global gene expression is measured using DNA microarrays and RNA-seq to quantify cellular RNAs. The focus then shifts to proteomics, the large-scale analysis of the full protein complement of a cell. Key methodologies described include mass spectrometry and tandem mass spectrometry for protein identification and sequencing, as well as "shotgun" methods for analyzing complex protein mixtures. Techniques for mapping protein localization, such as subcellular fractionation and immunofluorescence, are examined alongside methods for elucidating protein-protein interaction networks, including immunoprecipitation and the yeast two-hybrid system. Finally, the text defines systems biology as a field that seeks a quantitative understanding of integrated cellular behavior through computational modeling and large-scale experimentation. This includes systematic screens of gene function using CRISPR/Cas and RNA interference (RNAi), as well as the analysis of complex regulatory networks involving feedback loops and crosstalk. The chapter concludes with an introduction to synthetic biology, an engineering discipline aimed at creating new biological components and systems, illustrated by the development of genetic toggle switches, the engineered production of the antimalarial drug artemisinin, and the creation of cells with fully synthetic genomes.