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AP Bio



Unit 6

6.6 Gene Expression and Cell Specialization

1 min readmay 31, 2020


Lani Himegarner


RNA polymerase and transcription factors bind to promoters to initiate transcription. Promoters are located “upstream” of the start site so it can be determined whether the gene will be expressed before the enzymes reach the start site. 

Image courtesy of Giphy.

Some genes are negatively regulated, meaning a repressor is usually bound near the promoter to prevent transcription. These genes are not expressed by default and are therefore only made as needed. (The trp operon is a good example of this).

Gene Expression

Gene expression varies by what information from which genes are used to make a protein. Changing the genes used can even change the type of cell that is created. Gene expression affects cell products and protein function, and regulation of gene expression will consequently result in differential gene expression.
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