Prokaryotes, genes

Some Features of Prokaryotic Gene Expression Are Unique... 

Prokaryotic genes are often regulated in an on-off man-net in tesponse to simple environmental cues. Some eu-katyotic genes are regulated in the simple on-off man-... 

The structure and expression of a typical prokaryotic gene coding for a protein is illustrated in... 

RNA polymerase eventually reaches a transcription termination signal, at which point it will stop transcription and release the completed mRNA molecule. There are two kinds of transcription terminators commonly found in prokaryotic genes ... 

Prokaryotic genes encode protein sequences directly with no intervening noncoding DNA, so that mRNA transcripts serve as direct templates for protein synthesis. 

B. The lac operon of E coli is a good model for regulation of prokaryotic gene expression in response to environmental cues (Figure 12-4). 

The sequences of eukaryotic promoters are more variable than their prokaryotic counterparts (see Fig. 26-8). The three eukaryotic RNA polymerases usually require an array of general transcription factors in order to bind to a promoter. Yet, as with prokaryotic gene expression, the basal level of transcription is determined by the effect of promoter sequences on the function of RNA polymerase and its associated transcription factors. 

Many Prokaryotic Genes Are Clustered and Regulated in Operons... 

Provides an excellent account of the experimental basis of important concepts of prokaryotic gene regulation. 

Kustu, S., A. K. North, and D. S. Weiss, Prokaryotic transcriptional enhancers and enhancer-binding proteins. Trends Biochem. Sci. 16 397-401, 1991. First discovered in eukaryotes, enhancers have now been found to exist for a number of prokaryotic genes. 

Gene In marked contrast to prokaryotic genes where proteins are encoded by a... 

McCarthy, E.G. and Gualerzi, C. (1990) Translational control of prokaryotic gene expression. Trends Genet. 6, 78-85. 

Eukaryotic genes may be clustered (for example, genes for a metabolic pathway may occur on the same region of a chromosome) but are independently controlled. Operons or polycistronic mRNAs do not exist in eukaryotes. This contrasts with prokaryotic genes, where a single control gene often acts on a whole cluster (for example, lac I controls the synthesis of p-galactosidase, permease, and acetylase). 

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