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Topic: Lac operon

Related Topics

Lac repressor

Operon

Gene expression

Jacques Monod

Sequence motif

Gene regulatory network

RNA gene

Blast

Promoter

Sequence database

Sequence alignment

Gene knockout

Genetic code

RNA

Repeated Sequences

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	Reference.com/Encyclopedia/Lac operon
		Gene regulation of the lac operon was the first genetic regulatory mechanism to be elucidated and is often used as the canonical example of prokaryotic gene regulation.
		The lac repressor is a tetramer of identical subunits.
		The lac gene and its derivatives are amenable to use as a reporter gene in a number of bacterial-based selection techniques such as two hybrid analysis, in which the successful binding of a transcriptional activator to a specific promoter sequence must be determined.
	www.reference.com /browse/wiki/Lac_operon (3022 words)

	Lac operon Summary
		The Lac operon is an organized region of the genome that is present in the bacterium Escherchia coli.
		Gene regulation of the lac operon was the first genetic regulatory mechanism to be elucidated and is often used as the canonical example of prokaryotic gene regulation.
		Lac repressor is a tetramer of identical subunits.
	www.bookrags.com /Lac_operon (3409 words)

	Lac operon - Wikipedia, the free encyclopedia
		Gene regulation of the lac operon was the first genetic regulatory mechanism to be elucidated and is often used as the canonical example of prokaryotic gene regulation.
		The lac repressor is a tetramer of identical subunits.
		The lac gene and its derivatives are amenable to use as a reporter gene in a number of bacterial-based selection techniques such as two hybrid analysis, in which the successful binding of a transcriptional activator to a specific promoter sequence must be determined.
	www.sciencedaily.com /encyclopedia/lac_operon (3079 words)

	The Lactose Operon
		The lac operon, an inducible operon, is a mechanism used by bacterial cells as an economical means to restrict the expression of the structural genes necessary for metabolizing lactose, a disaccharide.
		The lac operon consists of three structural genes, Z, Y and A, which code for the enzymes necessary to catabolize lactose and a regulator gene, I, which codes for a regulator protein.
		While the transcription process of the lac operon is proceeding, the lac repressor gene is transcribed and a repressor protein is coded for.
	userpages.umbc.edu /~lrowan1/lactoseoperon.html (1059 words)

	Control of Gene Expression
		During normal growth on a glucose-based medium, the lac repressor is bound to the operator region of the lac operon, preventing transcription.
		However, in the presence of an inducer of the lac operon, the repressor protein binds the inducer and is rendered incapable of interacting with the operator region of the operon.
		The repressor of the operon is synthesized from the i gene.
	web.indstate.edu /thcme/mwking/gene-regulation.html (3248 words)

	The Operon
		Although repressors are free to diffuse through the cell, how does — for example — the lac repressor find the single stretch of 24 base pairs of the operator out of the 4.6 million base pairs of DNA in the E.
		Some of the genes in these operons appear — as in bacteria — to be involved in the same biochemical function, but this may not be the case for most.
		Absence of the lac repressor is essential but not sufficient for effective transcription of the lac operon.
	users.rcn.com /jkimball.ma.ultranet/BiologyPages/L/LacOperon.html (2173 words)

	Lac Operon
		One protein of the lac operon, called a permease, imports lactose through the otherwise-impermeable cell membrane.
		Ordinarily the repressor binds to the lac operon, shutting it off by physically interfering with expression of the operon.
		In the presence of the natural "inducer" allolactose (a by-product of lac β-galactosidase activity) or the artificial chemical inducer isopropylthiogalactoside (IPTG), however, the repressor binds to the inducer and releases the operon, allowing the lac operon enzymes to be synthesized by the cell.
	www.iscid.org /encyclopedia/Lac_Operon (193 words)

	The Lac Operon (Site not responding. Last check: )
		This assortment of genes and their regulatory regions is called the Lac operon.
		That means that when the cell is ready to use the operon, RNA polymerase is already there and waiting to begin transcription; the promoter doesn't have to wait for the holoenzyme to bind.
		We could say that the operon is primed for transcription upon the addition of lactose.
	web.mit.edu /esgbio/www/pge/lac.html (522 words)

	Induction of the lac Operon
		Illustration of the method by which the lac operon is transcribed.
		The lac operon in E.Coli is an example of that dual control.
		In an E. Coli cell growing in the absence of lactose, a repressor protein binds to the operator, preventing RNA polymerase from transcribing the lac operon's genes.
	www.accessexcellence.org /RC/VL/GG/induction.html (133 words)

	Molecular Genetics of Prokaryotes Problem Set (Site not responding. Last check: )
		An operon is a coordinately regulated unit of transcription in bacteria.
		The operon model was proposed by Jacob, Monod, and Wollman based on their genetic and biochemical studies on lactose-requiring mutations of E.
		The lac repressor, encoded by the lac I gene, is the regulatory protein of the lac operon.
	www.biology.arizona.edu /molecular_bio/problem_sets/mol_genetics_of_prokaryotes/01t.html (186 words)

	Prokaryotic Gene Regulation
		The operon is under the control of the adjacent lacI gene, encoding the lactose repressor.
		In the absence of allolactose, the inducer of the lac operon, the repressor tetramer binds to the lac operator (lacO) and prevents RNA polymerase from transcribing the operon.
		The lac operon is also under positive control by CRP (or cAMP Receptor Protein; also known as CAP or catabolite activator protein).
	oregonstate.edu /instruction/bb492/lectures/Regulation.html (958 words)

	Operon_tut
		An operon consists of all of the genes in a biochemical pathway, grouped together on the chromosome with ONE promoter controlling the transcription of all of the genes.
		The trp operon includes the 5 genes that encode the 5 enzymes necessary to convert a precursor molecule into the amino acid tryptophan.
		Because the trp operon is always ON (unless turned off by tryptophan), and the lac operon is always OFF (unless turned on by lactose).
	www.cofc.edu /poolel/Operon_tut.htm (1580 words)

	Bio572: The lac operon
		There are really two principal ways in which parts of the lac operon are used in molecular biology, and this is very important to understand.
		The lac Z gene may be used as a simple "reporter" gene, separated from its natural promoter.
		The reason this works is that the IPTG de-represses the lac operon, by binding to the lac repressor (the lac I gene product), preventing it from binding to the operator.
	www.escience.ws /b572/L11/L11.htm (1152 words)

	Bio572: The lac operon
		There are really two principal ways in which parts of the lac operon are used in molecular biology, and this is very important to understand.
		The lac Z gene may be used as a simple "reporter" gene, separated from its natural promoter.
		The reason this works is that the IPTG de-represses the lac operon, by binding to the lac repressor (the lac I gene product), preventing it from binding to the operator.
	escience.ws /b572/L11/L11.htm (1152 words)

	Lac operon (Site not responding. Last check: )
		Ancienne bergerie dominant le lac, transformée en gîte rural et chambres d'hôtes.
		Présentation de cette ville et du lac, de son histoire, du folklore savoyard et de ses paysages touristiques.
		Jardin en bordure du lac avec jeux pour enfants.
	www.omniknow.com /common/wiki.php?in=en&term=Lac_operon (4172 words)

	BioTech: The Lac Operon (Site not responding. Last check: )
		The lac operon consists of three structural genes entitled lacZ, lacY, and lacA.
		Immediately upstream from the lac operon is the lac I operon, which codes for the lac repressor protein.
		This enzyme has been found to not be necessary in the lac operon, nor is it necessary in the utilization of lactose.
	biotech.icmb.utexas.edu /pages/science/lac_operon.html (336 words)

	lac_operon
		This is a model of the regulation of gene expression based on the lac operon: a bacterial gene that produces an enzyme that breaks down lactose, a complex sugar, into simpler sugars: glucose and galactose.
		In this system, there are two genes: the lacI gene produces a repressor molecule which in turn binds to the operon of the lacZ gene which codes for beta-galactosidase, an enzyme.
		As long as the repressor is bound to the operon, the beta-galactosidase gene is turned off.
	bcrc.bio.umass.edu /netlogo/models/LacOperon (675 words)

	Prokaryotic Gene Expression
		Operon - a cluster of structural genes that are expressed as a group and their associated promoter and operator
		If lactose and glucose are present, the cell will use all of the glucose before the lac operon is turned on.
		The presence of this complex is closely associated with the presence of glucose in the cell.
	www.ndsu.nodak.edu /instruct/mcclean/plsc431/prokaryo/prokaryo2.htm (545 words)

	lac Operon: The Effect of Glucose and Cyclic AMP on the lac Operon
		lac Operon: The Effect of Glucose and Cyclic AMP on the lac Operon
		Concept 12: The Effect of Lactose in the Absence of Glucose on the lac Operon
		The presence or absence of glucose affects the lac operon by affecting the concentration of cyclic AMP.
	www.phschool.com /science/biology_place/biocoach/lacoperon/cyclic.html (139 words)

	NDSU Virtual Cell: Lac Operon -- The Repressor
		An operon is a series of genes linked together on the bacterial chromosome that are activated by a single promoter and produce a single mRNA molecule.
		Expression of the genes is turned off when a protein called the repressor binds to the promoter (red) and operator (orange) of the operon.
		Lactose must be added to to activate the lac operon.
	vcell.ndsu.nodak.edu /~christjo/vcell/animationSite/lacOperon/index.htm (212 words)

	The lac Operon Promoter
		The lac operon promoter (which regulates the transcription of lacZ, not lacI).
		Experimentally, it has been found that binding of the RNA polymerase to the lac promoter is relatively weak.
		Transcription of the lac operon often requires an activator such as catabolite activator protein (CAP).
	www.web-books.com /MoBio/Free/Ch4C2.htm (192 words)

	VCAC: Molecular Processes: Lac Operon
		The Lac Operon is an example of an inducible system of gene expression.
		Only when the right catalyst is added to the system, in this case the sugar lactose, is the process activated, allowing the genes in question to be expressed.
		An overview of the lac operon system and its key components.
	vcell.ndsu.nodak.edu /animations/lacOperon/index.htm (78 words)

	The Lac Operon: A Short History of a Genetic Paradigm (Site not responding. Last check: )
		In "The lac Operon - A Short History of a Genetic Paradigm" Benno Mueller-Hill does an excellent job of describing the history mistakes and present-day view of the lac operon.
		I found the middle section most interesting where the mistaken interpretations of the lac operon are considered.
		Finally the last section discusses the current model for how the lac Operon works; this model has not made it to many of the undergraduate molecular biology / Genetics textbooks yet.
	www.bioinformatics.vg /Books/th/The_Lac_Operon_A_Short_History_of_a_Genetic_Paradigm_3110148307.html (222 words)

	Modeling network dynamics: the lac operon, a case study -- Vilar et al. 161 (3): 471 -- The Journal of Cell Biology
		The lac repressor is encoded by lacI, which is immediately upstream of the operon.
		In this case, it is possible to study the dynamics of induction by considering as variables only the internal inducer concentration, the nonfunctional permeases, and the functional permeases.
		Coexistence of two types of networks in the lac operon is a population effect.
	www.jcb.org /cgi/content/full/161/3/471 (3402 words)

	CiteULike: Tag lac_operon
		Symmetric lac operator derivatives: effects of half-operator sequence and spacing on repressor affinity.
		Specific binding of lac repressor to linear versus circular polyoperator molecules.
		The Effect of Stochasticity on the Lac Operon: An Evolutionary Perspective
	www.citeulike.org /tag/lac_operon (233 words)

	VCAC: Molecular Processes: Lac Operon
		The Lac Operon is an example of an inducible system of gene expression.
		An overview of the lac operon system and its key components.
		An in-depth look at the major players and events that control the lac operon system.
	vcell.ndsu.edu /animations/lacOperon/index.htm (78 words)

	A New Pedagogy for the Lac-Operon
		If the students take a look at several bugs that gave red colonies on the red plates, they find that there is one that gives a positive ONPG test no matter what sugars were or were not around.
		The somatic chromosome is normal except that both the lac and pro operons are completely deleted.
		The pro+ operon is not needed and if the plasmid gets lost, no matter to the cell.
	www.science-projects.com /NewLac.htm (2201 words)

	lac operon definition - Dictionary - MSN Encarta
		lac operon definition - Dictionary - MSN Encarta
		Search for "lac operon" in all of MSN Encarta
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	encarta.msn.com /dictionary_561537014/lac_operon.html (84 words)

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