Chapter 15
... usually not transcribed (“off”) but can be turned on 3. Promoter usually capable of binding to RNA polymerase and therefore the genes are usually transcribed (“on”) but can be turned off D. The second and third situations imply that genes can be controlled (turned on or off). How? 1. Control of a pr ...
... usually not transcribed (“off”) but can be turned on 3. Promoter usually capable of binding to RNA polymerase and therefore the genes are usually transcribed (“on”) but can be turned off D. The second and third situations imply that genes can be controlled (turned on or off). How? 1. Control of a pr ...
Sample Questions for EXAM III
... Sample questions for EXAM III. Please ignore question numbering; your exam will consist of 40 multiple choice questions. These are questions lifted from previous exams. Remember, course content varies from year to year and what is emphasized in class changes from year to year. Use these questions as ...
... Sample questions for EXAM III. Please ignore question numbering; your exam will consist of 40 multiple choice questions. These are questions lifted from previous exams. Remember, course content varies from year to year and what is emphasized in class changes from year to year. Use these questions as ...
lac
... The system that induces the agalactosidase gene must require certain things in order to be effective. A close look at the two sugars shows what one of those things might be. The only difference between galactose and glucose is the position of the hydroxyl group on C4. This position is apparently ver ...
... The system that induces the agalactosidase gene must require certain things in order to be effective. A close look at the two sugars shows what one of those things might be. The only difference between galactose and glucose is the position of the hydroxyl group on C4. This position is apparently ver ...
OCR A Level Biology A Level Learner Resource 1
... This simulation lets you explore the activity of two structural genes and a regulatory gene in the bacterium Escherichia coli. This example of regulating genes in a prokaryote was the first type of control of gene expression to be discovered, in 1961 (Jacob and Monod). You can add and remove compone ...
... This simulation lets you explore the activity of two structural genes and a regulatory gene in the bacterium Escherichia coli. This example of regulating genes in a prokaryote was the first type of control of gene expression to be discovered, in 1961 (Jacob and Monod). You can add and remove compone ...
32_operons2
... – CAP detaches from the lac operon, – prevents RNA polymerase from binding to the promoter Promoter DNA ...
... – CAP detaches from the lac operon, – prevents RNA polymerase from binding to the promoter Promoter DNA ...
Molecular genetics of bacteria
... • Allo = other; steric = space. Many enzymes not only have an active site, but an allosteric site. • Binding of a molecule there causes a shape change in the enzyme. This affects its function. ...
... • Allo = other; steric = space. Many enzymes not only have an active site, but an allosteric site. • Binding of a molecule there causes a shape change in the enzyme. This affects its function. ...
Gene regulation in Bacteria
... - Negative control refers to transcriptional regulation by repressor proteins. - Positive control to regulation by activator proteins. - Small effector molecules affect transcriptional regulation. However, these bind to regulatory proteins and not to DNA directly. - In some cases, the presence of a ...
... - Negative control refers to transcriptional regulation by repressor proteins. - Positive control to regulation by activator proteins. - Small effector molecules affect transcriptional regulation. However, these bind to regulatory proteins and not to DNA directly. - In some cases, the presence of a ...
Key MW
... I- : mutant lacI gene -> no functional lac repressor is encoded IS: mutant lacI -> encodes a repressor protein to which lactose can no longer bind -> the repressor remains bound to the operator -> constitutive transcriptional repression Note: I+ is the wildtype lacI gene and encodes a normal repress ...
... I- : mutant lacI gene -> no functional lac repressor is encoded IS: mutant lacI -> encodes a repressor protein to which lactose can no longer bind -> the repressor remains bound to the operator -> constitutive transcriptional repression Note: I+ is the wildtype lacI gene and encodes a normal repress ...
Molecular Biology of Gene Function
... Question: what happens when both lactose and glucose are present together in the same cell? ...
... Question: what happens when both lactose and glucose are present together in the same cell? ...
Lecture 6, Exam III Worksheet Answers
... conditions, (when lactose isn’t present). It is preventing the RNA polymerase from binding and carrying out transcription. Is the lac repressor usually activated or inactive? Activated. It is already active, carrying out its role of repression, without any molecules attaching to it. What deactivates ...
... conditions, (when lactose isn’t present). It is preventing the RNA polymerase from binding and carrying out transcription. Is the lac repressor usually activated or inactive? Activated. It is already active, carrying out its role of repression, without any molecules attaching to it. What deactivates ...
Eukaryotic Gene Regulation
... WITHOUT Lactose- DNA binding protein is bound to the OPERATOR (where protein binds) so RNA polymerase CAN’T WORK (can’t make the mRNA) WITH Lactose- lactose binds to repressor DNA binding protein, this causes the protein to CHANGE SHAPE and FALL OFF the DNA Operator so RNA polymerase CAN WORK (trans ...
... WITHOUT Lactose- DNA binding protein is bound to the OPERATOR (where protein binds) so RNA polymerase CAN’T WORK (can’t make the mRNA) WITH Lactose- lactose binds to repressor DNA binding protein, this causes the protein to CHANGE SHAPE and FALL OFF the DNA Operator so RNA polymerase CAN WORK (trans ...
Regulatory genes
... 3 parts to an operon 1. Operator – controls access of RNA polymerase to the promoter 2. Promoter – where RNA polymerase attaches to begin transcription of genes 3. Genes – code for expression of proteins related to one particular function (e.g. breaking down galactosidase) ...
... 3 parts to an operon 1. Operator – controls access of RNA polymerase to the promoter 2. Promoter – where RNA polymerase attaches to begin transcription of genes 3. Genes – code for expression of proteins related to one particular function (e.g. breaking down galactosidase) ...
Problem Set 4B
... 4) For the following, indicate the genetic (what happens to the DNA sequence) and phenotypic effect, if any. If the phenotypic effect cannot be determined, indicate that it is “Unknown” in your answer. A. Nonsense mutation in the lacY gene. Nonfunctional permease. A stop codon is introduced in the p ...
... 4) For the following, indicate the genetic (what happens to the DNA sequence) and phenotypic effect, if any. If the phenotypic effect cannot be determined, indicate that it is “Unknown” in your answer. A. Nonsense mutation in the lacY gene. Nonfunctional permease. A stop codon is introduced in the p ...
Quiz on protein expression (Chiu lecture 3)
... polymerase gene. It also binds to the lac O operator that is part of the T7 promoter in front of the gene in pET vectors, which prevents T7 RNA polymerase from binding to the T7 promoter. b) Is the gene for T7 Polymerase encoded on the host or vector DNA? host c) What is the purpose of IPTG? IPTG co ...
... polymerase gene. It also binds to the lac O operator that is part of the T7 promoter in front of the gene in pET vectors, which prevents T7 RNA polymerase from binding to the T7 promoter. b) Is the gene for T7 Polymerase encoded on the host or vector DNA? host c) What is the purpose of IPTG? IPTG co ...
19.1 CONSTITUTIVE, INDUCIBLE AND REPRESSIBLE GENE
... The Lac promoter is intrinsically "weak" because of a poor match to consensus sequence of the sigma factor. This is important for positive regulation by CAP. The mechanism by which glucose regulates adenyl cyclase activity in this case is not yet known. It is interesting to note that cAMP is found a ...
... The Lac promoter is intrinsically "weak" because of a poor match to consensus sequence of the sigma factor. This is important for positive regulation by CAP. The mechanism by which glucose regulates adenyl cyclase activity in this case is not yet known. It is interesting to note that cAMP is found a ...
HANDOUT: CH 18 pt 1 Study
... CHAPTER 18 STUDY QUESTIONS, part 1 – Regulation of Gene Expression: Prokaryotes vs. Eukaryotes (p. 351-366) 1) What are the two levels within which metabolic control can occur in bacteria? ...
... CHAPTER 18 STUDY QUESTIONS, part 1 – Regulation of Gene Expression: Prokaryotes vs. Eukaryotes (p. 351-366) 1) What are the two levels within which metabolic control can occur in bacteria? ...
Gene Regulation - Cloudfront.net
... may stimulate the production of certain proteins) certain parts of eukaryotic chromosomes are in a highly condensed, compact state making it inaccessible to RNA polymerase some of these areas are structural and don’t contain genes other of these regions are functional genes that are not currently be ...
... may stimulate the production of certain proteins) certain parts of eukaryotic chromosomes are in a highly condensed, compact state making it inaccessible to RNA polymerase some of these areas are structural and don’t contain genes other of these regions are functional genes that are not currently be ...
Control Mechanisms
... when lactose is present in the cell When lactose is unavailable, the cell must block the production of β-galactosidase What’s an operon? A region of bacterial DNA that codes for a series of functionally related genes that are transcribed into one RNA ...
... when lactose is present in the cell When lactose is unavailable, the cell must block the production of β-galactosidase What’s an operon? A region of bacterial DNA that codes for a series of functionally related genes that are transcribed into one RNA ...
Control Mechanisms - Earl Haig Secondary School
... when lactose is present in the cell When lactose is unavailable, the cell must block the production of β-galactosidase What’s an operon? A region of bacterial DNA that codes for a series of functionally related genes that are transcribed into one RNA ...
... when lactose is present in the cell When lactose is unavailable, the cell must block the production of β-galactosidase What’s an operon? A region of bacterial DNA that codes for a series of functionally related genes that are transcribed into one RNA ...
Control of Gene Expression
... • The Lactose operon: negative inducible • The Tryptophan operon: negative repressible ...
... • The Lactose operon: negative inducible • The Tryptophan operon: negative repressible ...
Figure 18.19 Regulation of a metabolic pathway
... The gene for beta galactosidase is part of an operon, the lac operon, that includes two other genes coding for proteins that function in lactose metabolism ...
... The gene for beta galactosidase is part of an operon, the lac operon, that includes two other genes coding for proteins that function in lactose metabolism ...
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.