BSC 114 Study Guide - Final Guide: Coccyx, Lysozyme, Genome Evolution
24 Aug 2016
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Regulation of gene expression: mechanisms of regulation. Gene expression = gene to final product, all steps: gene (cid:0) mrna (cid:0) protein. Differential gene expression: each cell expresses only a subset of its genes. Gene regulation: mechanism of differential gene expression. Steps at which gene expression is regulated (in both proks and euks: *transcription, splicing (in euks only, translation, mrna stability, protein stability. All living organisms require the amino acid tryptophan. The bacterium e. coli can make tryptophan from a precursor molecule in 3 steps. However if tryptophan is available in the environment the enzymes are not expressed. The three trp enzymes are the products of 5 genes (two enzymes are dimer proteins) The 5 genes are adjacent and transcribed as a single long mrna. Operon: cluster of bacterial genes with similar functions. Operon is transcribed as one long mrna, so all genes turn on/off at the same time and equal amounts of protein are made.
