221_exam_3_2008
... Answer 3 of the 4 questions below. 6 pts each. 6 bonus points possible for answering all 4. The ideal antimicrobial drugs target unique characteristics of the organism to be inhibited. This makes it much more difficult to design drugs against eukaryotic microbes. We have discussed a few strategies i ...
... Answer 3 of the 4 questions below. 6 pts each. 6 bonus points possible for answering all 4. The ideal antimicrobial drugs target unique characteristics of the organism to be inhibited. This makes it much more difficult to design drugs against eukaryotic microbes. We have discussed a few strategies i ...
biology quiz chapter 12
... 4. If there are 64 possible codons and only 20 amino acids what has to be true? 5. Why does mRNA have to carry DNA’s message to the Ribosomes? 6. What two things are attached to tRNA? 7. Where in the cell does transcription occur? 8. Where in the cell does translation occur? 9. What are three possib ...
... 4. If there are 64 possible codons and only 20 amino acids what has to be true? 5. Why does mRNA have to carry DNA’s message to the Ribosomes? 6. What two things are attached to tRNA? 7. Where in the cell does transcription occur? 8. Where in the cell does translation occur? 9. What are three possib ...
Handout
... and how they are controlled What binds to the operator & when does this occur High levels of what substance affects how this operon how? 2. Why are genes under regulation? ...
... and how they are controlled What binds to the operator & when does this occur High levels of what substance affects how this operon how? 2. Why are genes under regulation? ...
Control of Gene Expression
... When lactose is not present in the cell, a repressor protein called the LacI protein binds to the operator and covers part of the promoter – they do overlap. This stops the RNA polymerase from binding from the promoter and transcribing their codes. The gene products are not made and the cell saves e ...
... When lactose is not present in the cell, a repressor protein called the LacI protein binds to the operator and covers part of the promoter – they do overlap. This stops the RNA polymerase from binding from the promoter and transcribing their codes. The gene products are not made and the cell saves e ...
Prokaryotic Gene Regulation (PowerPoint) Gulf Coast 2012
... Repressor protein binds inducer (Allolactose) and dissociates from operator RNA polymerase attaches to the promoter and synthesizes mRNA, dissociates at terminator Keep synthesizing mRNA until all Allolactose is gone (Situation # 3) ...
... Repressor protein binds inducer (Allolactose) and dissociates from operator RNA polymerase attaches to the promoter and synthesizes mRNA, dissociates at terminator Keep synthesizing mRNA until all Allolactose is gone (Situation # 3) ...
Regulation of Gene Action
... the transcription level. If lactose is added to the medium, the synthesis of both molecules is induced. ...
... the transcription level. If lactose is added to the medium, the synthesis of both molecules is induced. ...
Gene Regulation - public.iastate.edu
... The genes for lactose metabolism are: » clustered together on the chromosome » controlled by a single promoter » transcribed as a single transcript 1 promoter + several coding regions (cistrons) ...
... The genes for lactose metabolism are: » clustered together on the chromosome » controlled by a single promoter » transcribed as a single transcript 1 promoter + several coding regions (cistrons) ...
when glucose is scarce
... 1. A repressible operon is one that is usually on; binding of a repressor to the operator shuts off transcription. 1. The trp operon is a repressible operon. trp operon ...
... 1. A repressible operon is one that is usually on; binding of a repressor to the operator shuts off transcription. 1. The trp operon is a repressible operon. trp operon ...
What makes cells different from each other? How do cells respond to
... Growth on lactose depends on three enzymes: β-galactosidase Permease Thiogalactoside transacetylase ...
... Growth on lactose depends on three enzymes: β-galactosidase Permease Thiogalactoside transacetylase ...
Lecture 16 Gene Regulation
... The next major finding was the discovery of LacI– mutants. LacI– mutants are constitutive, meaning that they always express β-galactosidase at high levels regardless of whether there is an inducer present or not. LacI– mutants have apparently lost a component of the machinery the cell uses to turn ...
... The next major finding was the discovery of LacI– mutants. LacI– mutants are constitutive, meaning that they always express β-galactosidase at high levels regardless of whether there is an inducer present or not. LacI– mutants have apparently lost a component of the machinery the cell uses to turn ...
Gene Regulation in Prokaryotic Cells
... O. I+ is dominant to I-; I+ is trans-acting. The I+ gene product can regulate all structural lac operon genes, whether in cis or trans (residing on different DNA molecules) because the protein product of the I gene is able to diffuse and act on both operators in the partial diploid – Table 10-2, Fig ...
... O. I+ is dominant to I-; I+ is trans-acting. The I+ gene product can regulate all structural lac operon genes, whether in cis or trans (residing on different DNA molecules) because the protein product of the I gene is able to diffuse and act on both operators in the partial diploid – Table 10-2, Fig ...
lac Operon - Mediatech, Inc.
... An operon is a unit of gene expression and a transcriptionally-regulated system. The lac operon is responsible for producing the proteins that control the uptake of lactose for use as a carbon energy source when glucose is not available to the cell. It consists of three structural genes and a repres ...
... An operon is a unit of gene expression and a transcriptionally-regulated system. The lac operon is responsible for producing the proteins that control the uptake of lactose for use as a carbon energy source when glucose is not available to the cell. It consists of three structural genes and a repres ...
Control, Genomes and Environment
... • Bacteria produce enzymes to metabolise certain nutrients only when they are present in their environment. • E.coli normally respires glucose, but can also use lactose as its source of carbon. • The essential enzyme to allow the metabolism of lactose is b-galactosidase. • If lactose is not present, ...
... • Bacteria produce enzymes to metabolise certain nutrients only when they are present in their environment. • E.coli normally respires glucose, but can also use lactose as its source of carbon. • The essential enzyme to allow the metabolism of lactose is b-galactosidase. • If lactose is not present, ...
THE lac OPERON
... biochemical processes such as respiration • Other genes are not expressed all the time • They are switched on an off at need ...
... biochemical processes such as respiration • Other genes are not expressed all the time • They are switched on an off at need ...
bio12_sm_07_4
... uses tryptophan as a corepressor, which activates the repressor protein inhibiting gene expression. 4. Answers may vary. Sample answer: The lac operon regulates the production of the enzymes needed to metabolize lactose in the following ways: • In the absence of lactose, the upstream lacI gene synth ...
... uses tryptophan as a corepressor, which activates the repressor protein inhibiting gene expression. 4. Answers may vary. Sample answer: The lac operon regulates the production of the enzymes needed to metabolize lactose in the following ways: • In the absence of lactose, the upstream lacI gene synth ...
Chapter 21 (Part 2)
... clusters on the chromosome - called operons • This allows coordinated expression • A regulatory sequence adjacent to such a unit determines whether it is transcribed - this is the ‘operator’ • Regulatory proteins work with operators to control transcription of the genes ...
... clusters on the chromosome - called operons • This allows coordinated expression • A regulatory sequence adjacent to such a unit determines whether it is transcribed - this is the ‘operator’ • Regulatory proteins work with operators to control transcription of the genes ...
Chapter 15 Gene Regulation Prokaryotic Regulation
... enzymes that are required to process that molecule • This type of gene regulation (inducible vs. repressible) can be either positively regulated or negatively regulated ...
... enzymes that are required to process that molecule • This type of gene regulation (inducible vs. repressible) can be either positively regulated or negatively regulated ...
Control of Gene Express in Prokaryotes
... structural genes, located between the promoter and structural genes, contains the operator site. • Operator Site -region where the repressor attaches • Regulatory genes-codes for repressor proteins • Polycistronic mRNA-transcript for several polypeptides ...
... structural genes, located between the promoter and structural genes, contains the operator site. • Operator Site -region where the repressor attaches • Regulatory genes-codes for repressor proteins • Polycistronic mRNA-transcript for several polypeptides ...
Viruses as Pathogens in Bacterial Gene Regulation
... – can be switched off by the presence of a repressor bound to the operator » blocks attachment of the RNA Pol » product of a repressor gene that is some distance from the operon (trpR) » Repressors are reversible - only active if the corepressor is present to its ligand trp (allosteric inhibition) ...
... – can be switched off by the presence of a repressor bound to the operator » blocks attachment of the RNA Pol » product of a repressor gene that is some distance from the operon (trpR) » Repressors are reversible - only active if the corepressor is present to its ligand trp (allosteric inhibition) ...
doc NTC Mar 31
... Went through experimental approach to the negative regulation of the lac operon We know that this inducible and that it is negative control So if lactose is not present in the culture medium then the Laci gene is transcribed and is able to bind into the laci repressor protein, which is able to ...
... Went through experimental approach to the negative regulation of the lac operon We know that this inducible and that it is negative control So if lactose is not present in the culture medium then the Laci gene is transcribed and is able to bind into the laci repressor protein, which is able to ...
Control of Metabolic Pathways
... • Glucose is used in respiration by E.coli for energy release • E.coli can only make use of glucose in lactose if it is released from galactose • This is done by ß-galactosidase (enzyme) • E.coli’s chromosome has a gene that codes for ßgalactosidase • E.coli only produces ß-galactosidase in the pres ...
... • Glucose is used in respiration by E.coli for energy release • E.coli can only make use of glucose in lactose if it is released from galactose • This is done by ß-galactosidase (enzyme) • E.coli’s chromosome has a gene that codes for ßgalactosidase • E.coli only produces ß-galactosidase in the pres ...
DNA repair, transposable elements
... Regulating gene expression in prokaryotes In E. coli, some proteins are found at 5-10 copies/cell; others are found at 100,00 copies. How does a cell regulate the levels or amounts of different proteins at different times - in response to the environment? ...
... Regulating gene expression in prokaryotes In E. coli, some proteins are found at 5-10 copies/cell; others are found at 100,00 copies. How does a cell regulate the levels or amounts of different proteins at different times - in response to the environment? ...
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.