What would happen if RNA polymerase is not working properly?
If RNA polymerase malfunctions, one of the subunits of rRNA will not be transcribed from DNA. the two resulting DNA molecules each have one new DNA strand and one old strand from the original DNA molecule. both of the resulting DNA molecules are composed of new strands of nucleotides.
Under what circumstances would the lac operon be on versus off the trp operon?
Under what circumstances would the lac operon be “on“ versus “off”? The trp operon? The luc operon would be off when there is no lactose in the cell. The le operon would be on when luctose is present and there is little or no glucose in the cell.
What would occur if the repressor of an inducible operon were mutated so it could not bind the operator what would occur if the repressor of an inducible operon were mutated so it could not bind the operator?
If the repressor is mutated, it wont be able to bind to the operator region so the operon will go into continuous induced state. Operon genes will be transcribed continuously since there is no repressor molecule to halt the process.
What would happen if the operator was removed from the lac operon?
According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon? The lac operon would be transcribed continuously. Only lacZ would be transcribed.
Why is the lac operon usually switched off in E coli?
The lac operon of E. coli contains genes involved in lactose metabolism. It’s expressed only when lactose is present and glucose is absent. Two regulators turn the operon “on” and “off” in response to lactose and glucose levels: the lac repressor and catabolite activator protein (CAP).
What happens when both glucose and lactose are absent?
If both glucose and lactose are both present, lactose binds to the repressor and prevents it from binding to the operator region. If, however, glucose is absent and lactose becomes the only available carbon source, the picture changes. Lactose still prevents the repressor from binding to the operator region.
What happens to e coli When lactose is not present?
What happens to E. coli when lactose is not present? The genes that produce the enzymes needed to break down lactose are not expressed. The repressor protein blocks the genes from making mRNA.
What happens when E coli is grown with lactose?
In an E. coli cell growing in a growth medium containing glucose as the only carbon source, the lac operon is “off” (not being transcribed). If we add lactose to the growth medium, the lac operon remains “off”, with the cell continuing to utilize glucose.
What is the lac operon in E coli classic example of?
The lac operon is a classic example an inducible operon. When lactose is present in the cell, it is converted to allolactose. Allolactose acts as an inducer, binding to the repressor and preventing the repressor from binding to the operator. This allows transcription of the structural genes.
What is lac Z?
β-galactosidase. The LacZ protein codes for an enzyme called β-galactosidase, which is an essential part of the metabolism of lactose. It cleaves (separates) a single disaccharide lactose molecule into far more digestible glucose and galactose.
What happens when lac Z is mutated?
If this cell had alternative carbon sources to use for ATP production, like glucose or some other sugar, then the major consequence of a mutation in the lac Z gene would be the build up of lactose.
What does the lac Z gene do?
The gene product of lacZ is β-galactosidase which cleaves lactose, a disaccharide, into glucose and galactose. lacY encodes Beta-galactoside permease, a membrane protein which becomes embedded in the cytoplasmic membrane to enable the cellular transport of lactose into the cell.
Do humans have a lac operon?
Operons are common in bacteria, but they are rare in eukaryotes such as humans. In general, an operon will contain genes that function in the same process. For instance, a well-studied operon called the lac operon contains genes that encode proteins involved in uptake and metabolism of a particular sugar, lactose.
Is mutation lac operon?
Single mutants of the lac operon Such mutant are called constitutive mutants. Another type of mutant of lacI called Is prevents the repressor polypeptide from binding lactose, and thus will bind to the operator and be non-inducible.. This mutant constitutively represses the lac operon whether lactose is present or not.