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Transcription of lactose-metabolizing genes is blocked when?
Transcription of lactose-metabolizing genes is blocked when the Lac repressor protein binds to the operator region of the lac operon. This typically occurs in the presence of glucose when lactose is absent or in low concentrations. The Lac repressor prevents RNA polymerase from transcribing the genes, leading to inhibition of lactose metabolism.
Under which conditions are the lac structural genes expressed most efficiently?
The lac structural genes are expressed most efficiently in the presence of lactose and absence of glucose, as regulated by the lac operon in E. coli. When lactose is present, it binds to the lac repressor protein causing it to release from the lac operator, allowing RNA polymerase to bind and transcribe the structural genes. Glucose repression prevents catabolite repression, ensuring that the lac genes are expressed in the presence of lactose as the preferred carbon source.
What is allolactose and how does it work?
Allolactose isca sugar, isomeric with lactose, that is the true inducer of the lac operon. An agent capable of activating specific genes. A molecule that inhibits the action of the repressor of an operon, preventing it from freely binding with the operator gene and disabling its function.
What must happen for transcription of the lac operon genes to take place?
Lac operon is a set of genes that regulates the digestion of lactose. In absence of lactose in the medium, the repressor protein binds to the operator that inhibit the transcription of structural genes such as beta galactosidase, lactose permease and transacetylase. This makes sure to avoid the enzyme synthesis when there is no need!Conversely, when the lactose present in the medium, an isomer of lactose called allolactose bind to the repressor protein, the conformational change in the repressor let it to detach from repressor hence the RNA polymerase can transcribe the structural gene. Although this may be enough for synthesis of structual gene the system is tightly regulated by a protein called CAP (catabolite activator protein) and glucose.Glucose is a preferred source of energy for cell when this desirable source is present, lactose need not be used as a energy resource. What happens is there will be low level of cAMP when there is high amount of glucose and this keeps CAP inactive.When there is low glucose levels, the cAMP would be higher, that binds to CAP to make it active, which in turn binds to the promoter that enhance the transcription of structural genes.Thus, for efficient transcription lac operon structural genes, lactose must be present where glucose must be absent.
What would the presence of glucose indicate?
The presence of glucose indicates nothing other than the trivial fact that glucose is present.
Transcription of lactose-metabolizing genes is blocked when?
Transcription of lactose-metabolizing genes is blocked when the Lac repressor protein binds to the operator region of the lac operon. This typically occurs in the presence of glucose when lactose is absent or in low concentrations. The Lac repressor prevents RNA polymerase from transcribing the genes, leading to inhibition of lactose metabolism.
When is the lactose operon likely to be transcribed?
The lactose operon is likely to be transcribed in the absence of glucose and presence of lactose. When glucose is low and lactose is available, the inducer molecule allolactose binds to the repressor protein, causing it to be released from the operator region and enabling RNA polymerase to transcribe the operon.
Cellular respiration releases energy by breaking down glucose in the presence of what?
Oxygen!
What are oprons?
Operons are clusters of genes that consisting of one operator and promoter. There are two kinds of operons they are: Lac operon and try operons. The lac operon consist of clusters of 3 genes which are responsible for metabolism of glucose. When there is lactose in the environment the lac operons is transcript. The lactose binds to the repressor that was binding to the operator inhibiting the poly RNA to transcript the gene, but when lactose binds it causes the conformation to change and resulting in falling of the operator. When the repressor falls off the poly RNA can transcript the gene. When lactose is not present the repressor is activated and binds to the operator inhibiting poly RNA from transcribing the gene.The try operons consist of 5 genes under the control of one operator and promoter for synthesising trytopahan. When tryptophan is not present in the environment the gene is transcripted. When there no tryptophan the repressor is inactive and falls of the operator thus letting poly RNA transcriping the gene. When tryptophan is present there is no need in making the trypophan. The trypophan binds to the repressor activating and letting it bind to the operator and inhibiting the poly RNA from transcribing the gene.
Under which conditions are the lac structural genes expressed most efficiently?
The lac structural genes are expressed most efficiently in the presence of lactose and absence of glucose, as regulated by the lac operon in E. coli. When lactose is present, it binds to the lac repressor protein causing it to release from the lac operator, allowing RNA polymerase to bind and transcribe the structural genes. Glucose repression prevents catabolite repression, ensuring that the lac genes are expressed in the presence of lactose as the preferred carbon source.
A sentence for cellular respiration?
Cellular respiration releases energy by breaking down glucose in the presence of carbon dioxide.
Is it true cellular respiration releases energy by breaking down glucose in the presence of carbon diokide?
No that is not true.Presence of O2 is needed.
Does a glucose test strip measure the amount of glucose or just presence of glucose?
Just the presence of glucose Just the presence of glucose
How do you describe the process of cellular respiration?
Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.cellular respiration- process that release energy by breaking down glucose and food molecule in the presence of oxygen.
What are features of the lactose operon?
---|CRP|-------------| O |---| Z | Y | A |---CRP: Binding site for activatorO: Operator, binding site for repressorCoding sequences:Z: b-galactosidaseY: lactose permeaseA: thiogalactoside transacetlyase
What is the role of lactose in regulating lac operon expression?
When the lac operon controls the expression of proteins in the E.coli cell that can break down lactose into two sugars, glucose and galactose. When lactose is present, it binds to the repressor that typically sits on the lac operon, changing the repressor's conformation such that it can no longer bind to the lac operon. Because of this, RNA polymerase can now transcribe the gene into mRNA, which in turn is translated into the proteins that can break down lactose.
What is the reaction of oxygen and glucose?
Oxygen and glucose undergo a process called cellular respiration, where glucose is broken down in the presence of oxygen to produce energy, carbon dioxide, and water. This reaction releases ATP, which provides energy for the cell to carry out its functions.
