Control of Gene Expression

Control of Gene Expression - mRNA and translational...

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Control of Gene Expression Gene Regulation Is Necessary? By switching genes off when they are not needed, cells can prevent resources from being wasted. There should be natural selection favoring the ability to switch genes on and off. Complex multicellular organisms are produced by cells that switch genes on and off during development. A typical human cell normally expresses about 3% to 5% of its genes at any given time. Cancer results from genes that do not turn off properly. Cancer cells have lost their ability to regulate mitosis, resulting in uncontrolled cell division. Prokaryotes Much of our understanding of gene control comes from studies of prokaryotes . Prokaryotes have two levels of gene control. Transcriptional mechanisms control the synthesis of
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Unformatted text preview: mRNA and translational mechanisms control the synthesis of protein after mRNA has been produced. Operons Operons are groups of genes that function to produce proteins needed by the cell. There are two different kinds of genes in operons : Structural genes code for proteins needed for the normal operation of the cell. For example, they may be proteins needed for the breakdown of sugars. The structural genes are grouped together and a single mRNA molecule is produced during their transcription. Regulator genes code for proteins that regulate other genes. Operons have not been found in eukaryotes ....
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