Each of our cells contains all the information necessary to make a complete human being. However, not all the genes are expressed in all the cells. Genes that code for enzymes essential to basic cellular functions (e.g., glucose catabolism, DNA synthesis) are expressed in virtually all cells, whereas those with highly specialized functions are expressed only in specific cell types (e.g., rhodopsin in retinal pigment epithelium). Thus, all cells express: 1) genes whose protein products provide essential functions, and 2) genes whose protein products provide unique cell-specific functions. Thus, every organism has one genome, but many proteomes.
KeywordsRetinal Pigment Epithelium Codon Bias Glucose Catabolism Cysteine Thiol Basic Cellular Function
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