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Promoters
Promoters

... Tetracycline-dependent regulatory system - based on the E.coli Tn10-encoded tetracycline resistant operon - Tc resistance operon consists of two genes: a) the resistance gene TetA – codes for a membrane protein that exports invaded Tc out of the bacterial cell b) the regulator gene TetR – codes for ...
Gene regulation results in differential gene expression, leading to
Gene regulation results in differential gene expression, leading to

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Macromolecules Quiz
Macromolecules Quiz

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chapter 10
chapter 10

... d. the protein chain sends a signal through the nerve cells to the brain. ____ 21. In bacteria, a group of genes that code for functionally related enzymes, their promoter site, and the operator that controls them all function together as a(n) a. exon. c. operon. b. intron. d. ribosome. ____ 22. The ...
Expression system
Expression system

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Genomics and Gene Recognition
Genomics and Gene Recognition

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Characterization of Genes Expressed During the Early Stages of

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print last name first name

... (b)_______________________________ protein, causing it to dissociate from the operator so that (c)___________________________________ can now do its job by transcribing the DNA into mRNA. Positive regulation occurs when cyclic AMP binds to (d)_____________________________ forming a complex that bind ...
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Unit VII Study Guide

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Ch 18 Notes - FacStaff Home Page for CBU

... DNA methylation, the addition of methyl groups to certain bases in DNA, is associated with reduced transcription in some species. DNA methylation can cause long-term inactivation of genes in cellular differentiation. In genomic imprinting, methylation regulates expression of either the maternal or p ...
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Molecular Biology - Gene Regulation
Molecular Biology - Gene Regulation

... except in rare cases. Thus very little of the protein products of the three genes is made. When lactose is present, an end product of lactose metabolism binds to the repressor protein and prevents it from binding to the operator. This allows RNA polymerase to bind to the promoter and freely transcri ...
Checklist unit 18: Regulation of Gene Expression
Checklist unit 18: Regulation of Gene Expression

... As we learned in last week’s module, prokaryotes lack a nucleus, and mRNA transcription of DNA is immediately translated into a polypeptide (protein). As there is no additional processing of the mRNA in prokaryotic organisms, transcription is the only process during which gene regulation can occur. ...
Problem Set II Answer Key
Problem Set II Answer Key

... metabolizing trehalose into glucose, is contained within this bacterial operon. It is known that two DNA  binding proteins, TreA and TreB, are important for binding to the promoter of the Tre‐ase gene and are  involved in regulating the transcription of the Tre‐ase gene. TreA binds to the “A” site i ...
igor_ontologies_pathways
igor_ontologies_pathways

...  Different names for the same concept  Vast amounts of biological data from different ...
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Lac operon



lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available. Gene regulation of the lac operon was the first genetic regulatory mechanism to be understood clearly, so it has become a foremost example of prokaryotic gene regulation. It is often discussed in introductory molecular and cellular biology classes at universities for this reason.Bacterial operons are polycistronic transcripts that are able to produce multiple proteins from one mRNA transcript. In this case, when lactose is required as a sugar source for the bacterium, the three genes of the lac operon can be expressed and their subsequent proteins translated: lacZ, lacY, and lacA. The gene product of lacZ is β-galactosidase which cleaves lactose, a disaccharide, into glucose and galactose. LacY encodes lactose permease, a protein which becomes embedded in the cytoplasmic membrane to enable transport of lactose into the cell. Finally, lacA encodes galactoside O-acetyltransferase. Layout of the lac operon.It would be wasteful to produce the enzymes when there is no lactose available or if there is a more preferable energy source available, such as glucose. The lac operon uses a two-part control mechanism to ensure that the cell expends energy producing the enzymes encoded by the lac operon only when necessary. In the absence of lactose, the lac repressor halts production of the enzymes encoded by the lac operon. In the presence of glucose, the catabolite activator protein (CAP), required for production of the enzymes, remains inactive, and EIIAGlc shuts down lactose permease to prevent transport of lactose into the cell. This dual control mechanism causes the sequential utilization of glucose and lactose in two distinct growth phases, known as diauxie.
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