Lactose catabolism in E coliGroup of answer choicesIs maximal when lactose is present in the environmentIs normally a constitutive functionIs essential since it is the only sugar the bacterium can use as an energy sourceProduces lactose for the cell’s useIs controlled by a repressible operon
Question
Lactose catabolism in E coliGroup of answer choicesIs maximal when lactose is present in the environmentIs normally a constitutive functionIs essential since it is the only sugar the bacterium can use as an energy sourceProduces lactose for the cell’s useIs controlled by a repressible operon
Solution
Lactose catabolism in E. coli refers to the process by which the bacterium breaks down lactose to derive energy. This process is regulated by the lac operon, a set of genes that are turned on in the presence of lactose and off in its absence.
Here are the steps to answer the question:
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Lactose catabolism in E. coli is maximal when lactose is present in the environment. This is because the presence of lactose induces the lac operon, turning on the genes necessary for lactose catabolism.
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Lactose catabolism in E. coli is not normally a constitutive function. A constitutive function is one that is always active, regardless of environmental conditions. In contrast, lactose catabolism is regulated by the presence or absence of lactose.
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Lactose catabolism in E. coli is not essential since it is not the only sugar the bacterium can use as an energy source. E. coli can also metabolize other sugars, such as glucose.
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Lactose catabolism in E. coli does not produce lactose for the cell’s use. Instead, it breaks down lactose to derive energy.
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Lactose catabolism in E. coli is not controlled by a repressible operon. A repressible operon is one that is usually active but can be turned off by a specific molecule. In contrast, the lac operon is an inducible operon, which is usually off but can be turned on by a specific molecule (in this case, lactose).
So, the correct answer is: Lactose catabolism in E. coli is maximal when lactose is present in the environment.
Similar Questions
In the absence of lactose, the lac repressor is
Catabolite repression in E. coli primarily demonstrates how:Question 3Answera.The presence of glucose enhances the utilization of lactose.b.Lactose can increase the cAMP levels in the cell.c.Glucose presence inhibits lactose metabolism.d.Glucose and lactose are metabolized simultaneously.
The lac operon system, first described by Jacob and Monod, regulates lactose metabolism in . The is composed of a gene encoding a protein that normally keeps this operon in the position. Within the , the repressor binds to the , blocking transcription of structural genes needed for lactose metabolism. When is added to a cell's environment, it binds the repressor freeing the operator segment of the DNA. is now able to bind to the promoter, transcribing all three structural genes needed for lactose catabolism. When lactose again becomes depleted in the cell, the repressor binds to the operator blocking additional synthesis of enzymes from the .
The lac operon in E. coli is a coordinately controlled set of genes required for lactose metabolism. The operon and its associated regulatory sequences are shown in the following diagram.Two parallel horizontal lines are shown with a break between the first segment and the second segment. The first segment has a box labeled promoter and a box labeled lacI followed by an unlabeled black box. The second segment begins with an unlabeled black box, followed by a box labeled CAP site, a box labeled promoter, a box labeled operator and then 3 boxes with a bracket above them with the caption structural genes. The 3 boxes are labeled lacZ, lacY and lacA.The function of each locus shown in the diagram is listed in the table below.Part FunctionPromoter Binding site for RNA polymeraselacI Gene encoding the lac repressor proteinCAP site Binding site for the catabolite activator proteinOperator Binding site for the lac repressor proteinlacZ Gene encoding the beta-galactosidase proteinlacY Gene encoding the lactose permease proteinlacA Gene encoding the galactoside transacetylase proteinThe activity of the lac operon is influenced by the availability of lactose and glucose in the cellular environment. In the presence of lactose, the lac repressor protein is released from the operator, which allows the structural genes to be transcribed at a low level. If glucose (the preferred carbon source) is absent during this time, the catabolite activator protein binds to the CAP site, causing the structural genes to be transcribed at a higher level.Which of the following is the most likely result of a mutation in the lac repressor protein that prevents binding to the operator?Choose 1 answer:Choose 1 answer:(Choice A, Checked) The catabolite activator protein will not bind to the CAP site, even in the absence of glucose.AThe catabolite activator protein will not bind to the CAP site, even in the absence of glucose.(Choice B) The lacI gene will be highly expressed, even in the presence of glucose.BThe lacI gene will be highly expressed, even in the presence of glucose.(Choice C) The structural genes will not be transcribed, even in the presence of lactose.CThe structural genes will not be transcribed, even in the presence of lactose.(Choice D) The lactose permease protein will be produced, even in the absence of lactose.DThe lactose permease protein will be produced, even in the absence of lactose.
The inducer of the lac operon is lactose.
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