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Control of Gene Expression In many cells, only a small number of the genes present in the cell are being expressed. Another way of saying this is that the information in the genes for making particular proteins never results in the production of the protein in the cell. This is obvious if you think about it. For example, the proteins found in red blood cells are very different from the proteins found in muscle cells. However, both cell types in a given organism have exactly the same genes for making exactly the same proteins. This difference in protein content from one cell type to another in the cells of a given organism is due to selective gene expression - different genes get expressed in different cell types. Thus, red blood cells contain the protein hemoglobin that transports oxygen while muscle cells contain the proteins actin and myosin that allow the muscle cell to contract. The figure at this site illustrates the possible points of control. Note that the most common form of gene control is the failure of the gene to ever get transcribed. Why do you think that is the case?? In the inducible enzyme model at what point is gene control exerted? |
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I'm sure all of you have heard about DNA fingerprinting. Read about this process on page 245 of your text; then try the links under Forensics on the Biotech Applied page from Access Excellence. |
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