Genomes and the flow of biological information

This chapter provides an overview of genomes and the flow of biological information. Biological information is typically stored in the nucleic acid DNA referred to as the genome. A gene is typically defined as a region of DNA that controls a discrete hereditary characteristic. The first stage of gene expression is transcription, in which an RNA copy of the gene is synthesized. Messenger RNAs (mRNAs) are then translated to produce a protein product in a process mediated by the ribosome. The regulation of gene expression in both time and space is extensive and occurs at every level of expression. The chapter then looks at cellular infrastructure and gene expression. The overall expression of an organism's genome determines its phenotype—that is, its physical features and properties. The chapter also assesses the evolution of the genome and the tree of life, considering the process of natural selection.