Academic journal article Alcohol Research

Gene Structure and Gene Expression in Higher Organisms

Academic journal article Alcohol Research

Gene Structure and Gene Expression in Higher Organisms

Article excerpt

In higher organisms, including humans, the genes encoding the various components of the body are not just simple stretches of DNA that serve as a template from which proteins are generated. Instead, they have a complex structure involving, in some cases, dozens of pieces of coding sequences interspersed with noncoding sequences. The coding sequences, which are those parts of the gene that actually serve as templates for protein production, are called exons. The intervening noncoding sequences are known as introns (see Figure). In addition to the exons and introns, genes contain regulatory sequences that determine in which cell, at what time, and in what amount the gene is actively converted into the corresponding protein (i.e., is expressed). Most of these regulatory sequences are located in front of (i.e., upstream from) the start of the coding sequences; however, other regulatory elements may be located in introns or even behind (i.e., downstream from) the coding sequences. The promoter is a set of regulatory elements located closely near the start of the gene that also specify the exact start site where conversion of the DNA template into intermediary molecules begins. However, other regulatory elements may be located quite a distance away upstream of the gene.

Converting the genetic information contained in a gene on the DNA into a finished protein product is a complex process involving several steps. …

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