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CHAPTER 12
CHAPTER 12

... • The Bacterial Operon – An operon is a functional complex of genes containing the information for enzymes of a metabolic pathway. It includes: • Structural genes – code for the enzymes and are translated from a single mRNA. • Promoter – where the RNA polymerase binds. • Operator – site next to the ...
PPT2
PPT2

... enzymes required to metabolize lactose are only synthesized if glucose is depleted and lactose is available. ...
Notesheet
Notesheet

... Directions: Use the accompanying PowerPoint (available online) to complete this sheet. This sheet will be due upon the completion of the PowerPoint in class. These assignments are graded on a +/✓/- scale. 1. How many genes are transcribed and translated in human cells? 2. At minimum, how many protei ...
Gene regulation - Local.brookings.k12.sd.us
Gene regulation - Local.brookings.k12.sd.us

... if bacterium has enough tryptophan then it STOP doesn’t need to make enzymes used to build tryptophan  turn genes ON example if bacterium encounters new sugar (energy GO source), like lactose, then it needs to start making enzymes used to digest lactose ...
ORGANIC MOLECULES OF THE CELL
ORGANIC MOLECULES OF THE CELL

... This is due to its many hydroxyl groups. Recall that the hydroxyl functional group attracts water. Therefore, monosaccharides and disaccharides dissolve readily in water, forming sugary solutions. Starch and cellulose do not dissolve readily, but they do attract water. ...
LS1a Fall 09
LS1a Fall 09

... Section Activity #1: The lac operon represents a model system of prokaryotic gene regulation. (An ...
Chp 11 Notes
Chp 11 Notes

... 1. Gene Expression: the activation or "turning on" of a gene a. results in transcription and production of mRNA b. mRNA can then produce proteins c. Proteins are only made when they are needed 2. Genome: complete genetic makeup of an organism a. by regulating gene expression, cells control which par ...
Welcome to BISC 220 Cell Physiology Lab
Welcome to BISC 220 Cell Physiology Lab

... inducer of lac operon) ...
PartFourSumm_ThemesInRegulation.doc
PartFourSumm_ThemesInRegulation.doc

... operons, cAMP-CAP binds to a site centered at -42 and again increases the rate of transription. Note that the same regulatory protein (cAMP-CAP) can make different contacts with RNA polymerase at different operons and activate transcription by different mechanisms, affecting the affinity of the poly ...
Lecture Chpt. 18 Gene Regulation in Prokaryotic Organisms
Lecture Chpt. 18 Gene Regulation in Prokaryotic Organisms

... gene complex, consisting of a group of genes w/ related functions & DNA sequences that control them. ...
PPT File
PPT File

... sugar into the cell • -galactosidase—an enzyme that hydrolyses lactose ...
Gene expression Most genes are not expressed at a particular time
Gene expression Most genes are not expressed at a particular time

... contain specific sequences called transcription factor binding sites that are recognized by transcription factors (TFs). The binding of TFs to TF binding sites controls the expression of a gene. transcription factor binding site ...
12-5 Gene Regulation - Web hosting, domain name
12-5 Gene Regulation - Web hosting, domain name

... (Proteins), It Makes Them All At Once! – 3 Genes Turned On & Off Together. This is known as the lac ...
12-5 Gene Regulation
12-5 Gene Regulation

... (Proteins), It Makes Them All At Once! – 3 Genes Turned On & Off Together. This is known as the lac ...
Gene Regulation - Two Rivers High School
Gene Regulation - Two Rivers High School

... genetic material quickly to adjust to changing circumstances and new environments, since the failure to do so will cause not only death of the cell, but death of the organism itself. O Gene regulation allows such organisms to do things that will allow them to fit into hostile and extreme environment ...
Exam 2 Student Key
Exam 2 Student Key

... a. (2pts) Match the repressor structure with the most likely 1. frame shift early in coding LacI gene mutation. Each type of mutation will be used once. sequence 2 Repressor protein A: has normal protein sequence 2. silent mutation in 4th codon 3 Repressor protein B: cannot bind lactose, but it 3. S ...
10 new
10 new

... b. In the table, a superscript minus sign on a gene symbol merely indicates a mutant, but you know that some mutant behaviors in this system are given special mutant designations. Use the conventional gene symbols for the lac operon to designate each genotype in the table. (Problem 9 is from J. Kusp ...
The Genetics of Beta-galactosidase-
The Genetics of Beta-galactosidase-

... various lactose mutants. See Figure 1 for the operon model. For instance, z-mutants and y- mutants lost the ability to synthesize galactosidase and galactoside permease, respectively, regardless of the presence of an inducer. Constitutive mutants, i-, which were deficient in the lac repressor, acqui ...
Jacob/Monod
Jacob/Monod

... source. Lactose is cleaved into glucose and galactose by the enzyme beta-galactosidase, the galactose subsequently converted into more glucose, and the glucose used in primary metabolism. Bacterial cells actively growing on lactose each contain several thousand molecules of beta-galactosidase (up to ...
Bacterial species
Bacterial species

... -----------------------------------------------------------------------------------------------------------------This exam consists of 40 multiple choice questions worth 2.5 points each. On the separate testing form, please fill-in the single best choice for each question. Be sure to fill-out your s ...
Controlling Gene Expression in Bacteria
Controlling Gene Expression in Bacteria

...  E. coli is unlikely to encounter lactose, so it would be wasteful to produce the proteins needed to metabolize it unless necessary  Metabolizing lactose for energy only makes sense when two criteria are met: – Other more readily metabolized sugar (glucose) is unavailable – Lactose is available ©2 ...
Genetics - PCB 3063
Genetics - PCB 3063

... coordinate fashion, because they are present on the same mRNA. ...
Regulation of Gene Expression
Regulation of Gene Expression

... Repressor is active because there is no inducer to bind to it to turn it off no enzymes created (because none are needed) ...
File - EUREKA! Science
File - EUREKA! Science

...  Genes include more than just the protein-coding sequence ...
Foundations of Biology - Geoscience Research Institute
Foundations of Biology - Geoscience Research Institute

... to metabolize lactose  E. coli is unlikely to encounter lactose, so it would be wasteful to produce the proteins needed to metabolize it unless necessary  Metabolizing lactose for energy only makes sense when two criteria are met: – Other more readily metabolized sugar (glucose) is unavailable – L ...
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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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