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Transcription Factors - a specific nucleotide sequence in...

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Transcription Factors RNA polymerase requires the presence of general transcription factors before transcription can begin. Interactions between the transcription factors, RNA polymerase, and the promotor allow the polymerase to move along the gene and begin transcription. Higher levels of transcription occur with the presence of specific transcription factors as described below. The activators shown below are specific transcription factors. They function by binding to a region of the DNA called the enhancer . The enhancer may be located at a distance from the gene. Bending proteins assist in bending the DNA so that the enhancer is near the promoter. Activators, general transcripion factors, and other proteins attach, forming an initiation complex.Transcription begins when the initiation complex is formed. Hundreds of different transcription factors have been discovered; each recognizes and binds with
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Unformatted text preview: a specific nucleotide sequence in the DNA. A specific combination of transcription factors is necessary to activate a gene. Transcription factors are regulated by signals produced from other molecules. For example, hormones activate transcription factors and thus enable transcription. Hormones therefore activate certain genes. Posttranscriptional Control These mechanisms control or regulate mRNA after it has been produced. Alternative RNA Splicing This can produce variations in the mRNA produced. Different mRNA may have different introns removed. The removal of introns enables a gene to code for more than one different protein. An average human gene is thought to code for 3 different proteins. For example, experiments using radioactive labeling show that calcitonin produced by the hypothalamus is different from that produced by the thyroid. In each case, the same gene produces the protein....
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