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Background to gene regulation To understand the next part of my research, one needs some background in the molecular biology of cells. The traits of any organism are determined by their genes and the proteins encoded by those genes. Variable expression of those other genes can change the traits of that organism. These changes can be major structural changes or minor, transient changes. When a cell needs to express those traits, the information in the genes (in the form of DNA) is copied to a temporary form (messenger RNA, or mRNA) in a process called transcription. That mRNA is then used as a template to make the proteins themselves in a process called translation. Bacteria are very efficient organisms. Some of their genes are expressed all the time, but most are only expressed when the cell needs to exhibit the traits mediated by those genes. For example, bacteria love to grow on the sugar glucose and if it is present, usually it won't use any other sugar. It does this by not expressing the genes that encode proteins that uptake and metabolize those other sugars. However, if glucose is not present, the cell needs to find alternate sources. If lactose or arabinose is present, it will start to express the genes in the lactose or arabinose operons. An operon is a group of clustered genes that are transcribed and regulated together. In some cases, genes that are not clustered are still co-regulated. We call these genes part of a regulon. The process by which cells regulate the expression of genes in operons or regulons can be extremely complex. However, we can search for genes are that are specifically expressed in response to a stimulus and chances good are that those genes are important for responding to that condition.
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