Which gene controls transcription of chain A and chain B required for humulin synthesis in E. coli?

Options

A. `beta`-lactamase
B. `beta`-galactosidase
C. Poly galacturonase
D. Chitinase

Answer

To answer the question regarding which gene controls the transcription of chain A and chain B required for humulin synthesis in E. coli, we can break down the process step by step:

### Step 1: Understanding Humulin
Humulin is a form of human insulin that is produced using recombinant DNA technology. It consists of two chains, Chain A and Chain B, which are essential for its biological activity.

### Step 2: Role of E. coli
E. coli (Escherichia coli) is commonly used as a host organism for the production of recombinant proteins, including human insulin. It serves as a vector to express the insulin genes.

### Step 3: The Lac Operon
In E. coli, the lac operon is a well-studied model for gene regulation. It consists of structural genes (Z, Y, and A), a promoter, an operator, and a repressor gene. The lac operon is primarily involved in the metabolism of lactose, but it can also be utilized for the expression of foreign genes.

### Step 4: Gene Insertion
For the production of humulin, the genes coding for Chain A and Chain B of insulin are inserted into the E. coli genome. Typically, the gene for Chain A is inserted downstream of the lac operon, allowing it to be expressed when the operon is activated.

### Step 5: Transcription Control
The transcription of the inserted insulin genes (Chain A and Chain B) is controlled by the promoter region of the lac operon. The expression of these genes occurs when the lac operon is activated, which is usually in the presence of an inducer (such as IPTG) that inactivates the repressor.

### Step 6: Conclusion
The gene that controls the transcription of Chain A and Chain B required for humulin synthesis in E. coli is the **lac promoter** associated with the lac operon. This promoter drives the transcription of the inserted insulin genes.

### Summary
In summary, the lac promoter from the lac operon in E. coli controls the transcription of the genes coding for Chain A and Chain B of humulin.

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