Question

In: Biology

Please correct if they are wrong Genotype ?-galactosidase Permease Outcome Lactose No lactose Lactose No lactose...

Please correct if they are wrong

Genotype

?-galactosidase

Permease

Outcome

Lactose

No lactose

Lactose

No lactose

I+P+O+Z-Y-/

I+P+O+Z-Y-

+

-

+

-

lac+

ISP+OCZ+Y-/

I+P-OCZ-Y+

-

-

-

-

lac-

I+P+O+Z+/

I+P+O+Z+

+

-

-

-

lac+

Solutions

Expert Solution

Lac operon is an inducible operon which means that the cistron undergoes transcription only when lactose is prsent in the medium. This is because the lac operon encodes for lactose-fermentation enzymes, hence presence of lactose in the cell/medium will prompt the cells to induce the operon. The lac operon contains a cistron carrying three genes. The lac Z encodes for beta galactosidase, lac Y encodes for permease and lac A encodes for transacetylase. All of these three genes need to be present and expressed for a successful lac operon transcription.

Thus, based upon these information, the answers can be found as below:

Case 1: No expression (the genotype is both negative for lacZ and Y, hence no transcription will take place)

Case 2: No expression (the expression of lac operon is absent in the absence of lactose in the medium)

Case 3: No expression (Since the lac Y gene is altogether absent from the cistron, no expression of cistron takes place)


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