A bacterial cell was transformed with a recombinant DNA that was generated using a human gene. However, the transformed cells did not produce the desired protein. Reason could be

Options

A. human gene may have intron which bacteria cannot process
B. amino acid codons for humans and bac- teria are different
C. human protein is formed but degraded by bacteria
D. all of the above

Answer

To solve the question regarding why a bacterial cell transformed with a recombinant DNA containing a human gene did not produce the desired protein, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Transformation Process**:
- A bacterial cell is transformed with recombinant DNA that includes a human gene. This process is intended to allow the bacteria to produce a specific human protein.

2. **Identifying the Human Gene Characteristics**:
- Human genes often contain non-coding regions called introns. These introns are removed during the process of RNA splicing in eukaryotic cells, resulting in mature mRNA that is translated into proteins.

3. **Bacterial Gene Expression**:
- Bacteria, being prokaryotes, do not have the machinery for RNA splicing. This means that if a human gene with introns is introduced into a bacterial cell, the introns will remain in the mRNA.

4. **Consequences of Introns in Bacteria**:
- Since bacteria cannot process introns, the presence of these non-coding regions in the mRNA can prevent the proper translation of the protein. The bacterial ribosomes will not be able to translate the mRNA correctly, leading to the failure to produce the desired protein.

5. **Evaluating Other Possible Reasons**:
- While considering other options:
- The statement about different amino acid codons for humans and bacteria is incorrect because the genetic code is universal; thus, the codons for amino acids are the same across species.
- The notion that human proteins are formed but degraded by bacteria is also incorrect, as the protein is not formed at all due to the introns.

6. **Conclusion**:
- The primary reason the transformed bacterial cells did not produce the desired protein is that the human gene may contain introns, which bacteria cannot process. Therefore, the correct answer is that the human gene may have introns which bacteria cannot possess.