mRNA in prokaryotes is usually

Options

A. monocistronic
B. polycistronic
C. monokaryotic
D. replicative

Answer

To answer the question "mRNA in prokaryotes is usually," we need to understand the characteristics of mRNA in prokaryotic organisms. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understand Prokaryotic Cells**:
- Prokaryotic cells are unicellular organisms that lack a membrane-bound nucleus and organelles. This is a fundamental characteristic that distinguishes them from eukaryotic cells.

2. **Definition of mRNA**:
- Messenger RNA (mRNA) is a type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized.

3. **Monocistronic vs. Polycistronic mRNA**:
- **Monocistronic mRNA**: This type of mRNA carries the information for a single gene. It is common in eukaryotes.
- **Polycistronic mRNA**: This type of mRNA can encode multiple proteins from a single mRNA molecule. It is typical in prokaryotes, where several genes can be transcribed together.

4. **Characteristics of Prokaryotic mRNA**:
- In prokaryotes, mRNA is often polycistronic, meaning that it can contain the coding sequences for multiple genes. This allows for the coordinated expression of genes that are functionally related.

5. **Conclusion**:
- Therefore, the mRNA in prokaryotes is usually polycistronic.

### Final Answer:
The mRNA in prokaryotes is usually **polycistronic**.

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