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Overview of the Respiratory System

Author(s): Nancy Moreno, PhD, Deanne Erdmann, MS, and Sonia Rahmati Clayton, PhD
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Regulation of the Human Genome (I)

The expression of genes within the human genome is controlled by a number of different mechanisms. Promoters, enhancers and silencers are segments of DNA that regulate the rate and amount of transcription, or expression, of nearby genes. Transcription is the process of synthesizing RNA as a messenger in order to implement the instructions encoded within DNA. Promoters are generally located immediately upstream from the first exon (coding segment of DNA) of a gene. Enhancers are genetic elements that increase transcription of associated genes. Silencers are genetic elements that suppress transcription of associated genes. Enhancers and silencers can be located some distance away from a promoter, may be upstream or downstream of the promoter on which they act, and can be effective even at considerable genetic distances.