Question

Gene regulation governing lactose operon of E. coli that involves the lac I gene product is?
A)Negatively and repressible because repressor protein prevents transcription.
B)Feedback inhibition because excess of beta-galactosidase can switch off transcription.
C)Positive and inducible because it can be induced by lactose.
D)Negative and inducible because repressor protein prevents transcription.

Answer 1

Gene regulation is of different types; they have different pathways for regulation and regulation takes place at the time of transcription. To regulate the specific gene there are unique regulating molecules in bacteria that are transcribed into mRNA.

Complete answer:
Let us study the options to find the correct answer:
Option A: Negatively and repressible operon is activated then the operon's voice will not be active and it will get transcribed in the operon. Therefore, this is an incorrect answer.

Option B: Feedback inhibition is the mechanism of cellular control which helps the enzyme's end product to inhibit the activity of the enzyme. Therefore, this is an incorrect option.

Option C: In the positive and inducible operon, the positive control will bind to the DNA for an activator protein transcription. Therefore, this is an incorrect answer.

Option D: Genes are in a cluster form located in bacteria on the chromosome, with the help of a promoter they are transcribed i8n 6the form of the single unit where the promoter is referred to as an operon. Operons are uncommon in humans but common in bacteria. In a negatively inducible operon, there is a regulatory repressor protein bind to it which helps to prevent the gene from being transcribed in the operon so if with the presence of an inducer molecule, it confirms the repressor so that it cannot bind to the operator. This negatively inducible operon is the lac operon and the allolactose is the inducer molecule. Therefore, this is the correct answer.

Hence, the correct answer is option (D)

Note: The importance of gene regulation is as follows,
1)It ensures that only the gene that are needed at a particular time are expressed
2)It helps in organism to respond to its neighbouring environment