Regulation Of Gene Expression PDF

Regulation of Gene Expression Part I  Learning Outcomes 1.Outline the four levels of control of 7.Explain how secondary RNA gene expression and describe examples structures can regulated gene of each level in eukaryotes and expression in prokaryotes with prokaryotes....

Regulation of Gene Expression Part I  Learning Outcomes 1.Outline the four levels of control of 7.Explain how secondary RNA gene expression and describe examples structures can regulated gene of each level in eukaryotes and expression in prokaryotes with prokaryotes. reference to riboswitches and trp 2.Draw and label the structure of a operon attenuation bacterial operon 8.Describe the regulation of iron 3.Describe the regulation of a response element in eukaryotes repressible operon using the lac operon and contrast it to riboswitches as an example and operons 4.Describe the regulation of an inducible 9.Define proteome and operon using the trp operon as an transcriptome example 10.Outline the principles of 5.Contrast negative and positive control RNAseq, qPCR, microarrays, mass of gene expression in bacteria spectrometry, Western blots, and antibody arrays, and explain how 6.Describe an example of positive these techniques are used in control of gene expression with reference to cAMP control of the lac biology and medicine Gene expression Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. Products are often proteins Non-protein coding genes such as ribosomal RNA (rRNA), transfer RNA (tRNA) or small nuclear RNA (snRNA) genes, the product is a functional RNA. Eukaryotes ,prokaryotes A gene product is the biochemical material, either RNA or protein, resulting from expression of a gene. Importance of regulation of G.E By altering gene expression, organisms can adapt to environmental challenges. Transcription control can result in tissue specific gene expression. Gene regulation is influenced by hormones, heavy metals and chemicals. Dysregulation of gene regulation can lead to disease. Positive regulation and negative regulation.  A positive regulator, an enhancer or activator mediates positive regulation.  Inhibition of a negative regulator also results in positive regulation. A negative regulator, a silencer or repressor mediates negative regulation. An inducible gene- expression increases in response to an inducer or activator, have low basal rate of transcription. Genes with high basal rate are down regulated by repressors and called repressible genes.  Lac operon Operon is a cluster of structural genes that are expressed as a group and their associated promoter and operator. The lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and some other enteric bacteria. It has three adjacent structural genes, lacZ, lacY, and lacA. lac Operon Gene Gene Function I Gene for repressor protein P Promoter O Operator lac Z Gene for ß-galactosidase lac Y Gene for ß-galactoside permease lac A Gene for ß-galactoside transacetylase  Example of positive control of gene expression with reference to cAMP control of the lac operon In the presence of lactose or isopropyl thiogalactoside (IPTG), a lactose analog results in the induction of lac operon enzymes.  Bacterium accumulates cAMP when it is starved for carbon source. Lactose is not the preferred carbohydrate source for E. coli. glucose is utilized first.  In absence of glucose, bacteria will need to metabolize glucose alternative like lactose, and the lac operon is turned on. The promoter of the lac operon has two binding sites. One site is the location where RNA polymerase binds. The second location is the binding site for catabolite activator protein (CAP) and cyclic AMP (cAMP) complex resulting in the induction of lac operon enzymes.