If lacO were mutated, what effect would this have on lactose metabolism? If lacO
ID: 41972 • Letter: I
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If lacO were mutated, what effect would this have on lactose metabolism?
If lacO were mutated, what effect would this have on lactose metabolism? The repressor would not property bind to the operator, and the lac operon would be over expressed. The repressor would not property bind to the operator, and the lac operon would be under expressed. One of the enzymes that are involved in lactose metabolism would not be able to carry out its reaction, and lactose would not be metabolized. RNA polymerase would not property bind to the promoter, and the lac operon would be under expressed. The repressor protein would not function properly, and the lac operon would be over expressed.Explanation / Answer
The lac operon contains two types of genes, which includes structural genes and regulatory genes. The genes that can be transcribed into mRNA (messenger ribonucleic acid) come under structural genes. There are three structural genes present in the lac operon, they are lac z, lac y, and lac i. There are two regulatory genes present in lac operon that includes the operator and the promoter, which cannot be transcribed.
The repressor protein synthesized by gene ‘i’ binds to operator (lac-O) to inhibit transcription. The lac repressor binds to operator in the absence of lactose. If the bacterium is living in the absence of lactose and lactose is suddenly introduced into the bacterium's environment, then immediately the high concentration of lactose in the cell binds to the repressor and makes operator unfit for binding to repressor. Thus, the RNA polymerase can then transcribe the structural genes.
A mutation in Operator gene (lac-O) causes constitutive expression of a protein. The reason behind is that this mutation modifies the structure of an operator gene. As a result, repressor no longer binds to operator, and RNA (ribonucleic acid) polymerase initiates transcription continuously.
Thus, the correct option among the following is “The repressor would not properly bind to the operator, and the lac operon would be over expressed”.
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