Lecture 10: Control of gene expression
... close to lac operon. These mutations caused constitutive phenotype (Lac++), and it was concluded that they affect ‘inducibility’ locus. Hence the name lacI. The lacI gene encodes lac repressor that inhibits the lac lacZ- or lacY- mutations cause Lac- phenotype operon. The operon is derepressed by la ...
... close to lac operon. These mutations caused constitutive phenotype (Lac++), and it was concluded that they affect ‘inducibility’ locus. Hence the name lacI. The lacI gene encodes lac repressor that inhibits the lac lacZ- or lacY- mutations cause Lac- phenotype operon. The operon is derepressed by la ...
Slide 1
... binding of a REPRESSOR to the operator shuts off transcription ● The trp operon is a repressible operon ● An inducible operon is one that is usually off; a molecule called an INDUCER inactivates the repressor and turns on transcription ● The classic example of an inducible operon is the lac operon, ...
... binding of a REPRESSOR to the operator shuts off transcription ● The trp operon is a repressible operon ● An inducible operon is one that is usually off; a molecule called an INDUCER inactivates the repressor and turns on transcription ● The classic example of an inducible operon is the lac operon, ...
Chapter 15
... Recall that lactose breaks down into glucose and galactose. Low glucose levels signals the cell for more lactose to be broken down. Both conditions must be met for the lac operon to turn on. ...
... Recall that lactose breaks down into glucose and galactose. Low glucose levels signals the cell for more lactose to be broken down. Both conditions must be met for the lac operon to turn on. ...
Gene Expression
... What would happen if the repressor of an operon were mutated so that it could not bind to the operator? a) irreversible binding of the repressor to the promotor. b) reduced transcription of the operon’s genes c) continuous transcription of the operon’s genes ...
... What would happen if the repressor of an operon were mutated so that it could not bind to the operator? a) irreversible binding of the repressor to the promotor. b) reduced transcription of the operon’s genes c) continuous transcription of the operon’s genes ...
Microbial Genetics
... (new) strand; thereby, the two daughter strands form in opposite directions due to the antiparallel orientation of the two parent (template) strands. • DNA Polymerase has the ability to “proof reading” its work and to correct any mismatched base pairs. It is so good that errors only happen once in a ...
... (new) strand; thereby, the two daughter strands form in opposite directions due to the antiparallel orientation of the two parent (template) strands. • DNA Polymerase has the ability to “proof reading” its work and to correct any mismatched base pairs. It is so good that errors only happen once in a ...
Review Topics for Final Part 2
... — What types of genes does LexA repress? When would you want to turn on those genes? — RecA protein promotes self-cleavage of the LexA repressor, but only when RecA is bound to what? Regulation of ribosomal proteins and rRNA: — When ribosomal proteins are in excess, how do they prevent synthesis o ...
... — What types of genes does LexA repress? When would you want to turn on those genes? — RecA protein promotes self-cleavage of the LexA repressor, but only when RecA is bound to what? Regulation of ribosomal proteins and rRNA: — When ribosomal proteins are in excess, how do they prevent synthesis o ...
Gene Expression Prokaryotes and Viruses
... Imaging of luciferase expression in tissue sections of the brain of a transgenic mouse. With the powerful overlay technique, luminescence signals can be superimposed onto the brightfield image, to localize gene expression. (Courtesy B. ...
... Imaging of luciferase expression in tissue sections of the brain of a transgenic mouse. With the powerful overlay technique, luminescence signals can be superimposed onto the brightfield image, to localize gene expression. (Courtesy B. ...
Communication - Miss Hanson's Biology Resources
... E. coli only produce enzymes needed to metabolise lactose when lactose is present in the substrate ß-galactosidase: ▪ catalyses hydrolysis of lactose. Lactose permease: ▪ transports lactose into the cell. ...
... E. coli only produce enzymes needed to metabolise lactose when lactose is present in the substrate ß-galactosidase: ▪ catalyses hydrolysis of lactose. Lactose permease: ▪ transports lactose into the cell. ...
in Power-Point Format
... 4. Why are negative and positive control of the lac operon important to the neergy efficiency of E. coli cells? 14. Diagram how arabinose relieves repression in the araBAD operon. Show whereAraC is located (a) in the absence of arabinose; (b) in the presence of arabinose and lack glucose. See Fig. 3 ...
... 4. Why are negative and positive control of the lac operon important to the neergy efficiency of E. coli cells? 14. Diagram how arabinose relieves repression in the araBAD operon. Show whereAraC is located (a) in the absence of arabinose; (b) in the presence of arabinose and lack glucose. See Fig. 3 ...
Gene Regulation
... Gene Regulation • In 1961, Francois Jacob and Jacques Monod proposed the operon model for the control of gene expression in bacteria. • An operon consists of three elements: – the genes that it controls, • In bacteria, the genes coding for a protein are transcribed (or not) as one long mRNA molecule ...
... Gene Regulation • In 1961, Francois Jacob and Jacques Monod proposed the operon model for the control of gene expression in bacteria. • An operon consists of three elements: – the genes that it controls, • In bacteria, the genes coding for a protein are transcribed (or not) as one long mRNA molecule ...
Chapter 7 Operons: Fine Control of Bacterial Transcription Bacterial
... • 21. Why does translation of the trp leader region not simply continue into the trp structural genes (trpE, etc.) in E. coli ? • AQ 3. Consider E. coli cells each having one of the following mutations: Indicate effect each mutation on function of lac operon (assuming no glucose is present): a. muta ...
... • 21. Why does translation of the trp leader region not simply continue into the trp structural genes (trpE, etc.) in E. coli ? • AQ 3. Consider E. coli cells each having one of the following mutations: Indicate effect each mutation on function of lac operon (assuming no glucose is present): a. muta ...
1st set of Journal Clubs this Wednesday!
... •Induction refers to increased expression of genes in response to a metabolite. •Repression refers to decreased expression of genes in response to a metabolite. •IPTG, the artificial inducer of the lac operon, is an example of a ‘gratuitous’ inducer: It cannot be metabolized by β-galactosidase enzym ...
... •Induction refers to increased expression of genes in response to a metabolite. •Repression refers to decreased expression of genes in response to a metabolite. •IPTG, the artificial inducer of the lac operon, is an example of a ‘gratuitous’ inducer: It cannot be metabolized by β-galactosidase enzym ...
Gene Regulation
... Lactose binds to repressor, causing shape change; repressor falls off DNA, allows unhindered transcription by RNA polymerase. Translation of mRNA results in enzymes needed to use lactose. ...
... Lactose binds to repressor, causing shape change; repressor falls off DNA, allows unhindered transcription by RNA polymerase. Translation of mRNA results in enzymes needed to use lactose. ...
lacI
... An operon is a single transcriptional subunit that includes a series of structural genes, a promoter and an operator Separate regulator gene with its own promoter ...
... An operon is a single transcriptional subunit that includes a series of structural genes, a promoter and an operator Separate regulator gene with its own promoter ...
BIO 208 TERMS AND OBJECTIVES s08 Objectives Unit 2 Ch 4, 11
... promoter that allows for the regulation of gene expression of GFP by arabinose sugar 26. To transform competent E. coli with a GFP-containing plasmid (lab) 27. To calculate transformation efficiency (colonies/ug DNA) from given data (lab) 28. To contrast constitutively expressed housekeeping genes a ...
... promoter that allows for the regulation of gene expression of GFP by arabinose sugar 26. To transform competent E. coli with a GFP-containing plasmid (lab) 27. To calculate transformation efficiency (colonies/ug DNA) from given data (lab) 28. To contrast constitutively expressed housekeeping genes a ...
Power Point for Lecture 9
... produces a “bad” subunit, which is not only itself unable to bind to operator DNA, but is also able to act as part of a tetramer to prevent any “good” (wild type LacI) subunits from binding. Pi lacI- P O ...
... produces a “bad” subunit, which is not only itself unable to bind to operator DNA, but is also able to act as part of a tetramer to prevent any “good” (wild type LacI) subunits from binding. Pi lacI- P O ...
Controlling Gene Expression
... • Transcription is normally off • Repressor is active (fits into operator) • Need an outside molecule from environment to inactivate repressor • Inducer has the role of inactivating repressor • Proteins produced through transcription are enzymes. • Enzymes break down inducer. • Inducer is absent wh ...
... • Transcription is normally off • Repressor is active (fits into operator) • Need an outside molecule from environment to inactivate repressor • Inducer has the role of inactivating repressor • Proteins produced through transcription are enzymes. • Enzymes break down inducer. • Inducer is absent wh ...
Readings Problems Background Week 8
... By conducting matings with various combinations of i, z and y genes, and testing for the production of β-galactosidase in the presence and absence of inducer as a function of time after initiating the mating, Pardee, Jacob and Monod demonstrated that i+ is trans-acting and dominant to i-. Thus, an i ...
... By conducting matings with various combinations of i, z and y genes, and testing for the production of β-galactosidase in the presence and absence of inducer as a function of time after initiating the mating, Pardee, Jacob and Monod demonstrated that i+ is trans-acting and dominant to i-. Thus, an i ...
Chapt16_lecture
... – trp repressor binds to the operator to block transcription – binding of repressor to the operator requires a corepressor which is tryptophan – low levels of tryptophan prevent the repressor from binding to the operator ...
... – trp repressor binds to the operator to block transcription – binding of repressor to the operator requires a corepressor which is tryptophan – low levels of tryptophan prevent the repressor from binding to the operator ...
File - need help with revision notes?
... temperate climates. Sunlight there was not intense enough to cause vitamin D production in those with dark skin, so they would suffer form rickets. ...
... temperate climates. Sunlight there was not intense enough to cause vitamin D production in those with dark skin, so they would suffer form rickets. ...
THE LAC OPERON
... Some operons work differently than the Lac operon. These are called Repressible Operons. The example is the Trp OPERON In the Trp operon, tryptophan is synthesized because the gene is always turned on unless the inducer is present. Normally, the gene is turned off because tryptophan is present and ...
... Some operons work differently than the Lac operon. These are called Repressible Operons. The example is the Trp OPERON In the Trp operon, tryptophan is synthesized because the gene is always turned on unless the inducer is present. Normally, the gene is turned off because tryptophan is present and ...
pdf
... fragement, oc, plus repressor will not bind). Electrophoretic mobility shift assays would be used now in many cases. [3] This ability of particular sequences to bind with high affinity to the desired protein is frequently exploited to rapidly isolate the protein. The binding site can be synthesized ...
... fragement, oc, plus repressor will not bind). Electrophoretic mobility shift assays would be used now in many cases. [3] This ability of particular sequences to bind with high affinity to the desired protein is frequently exploited to rapidly isolate the protein. The binding site can be synthesized ...
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.