Eukaryotic mRNAs are associated with proteins to form ribonucleoprotein complexes. Some of these may remain in cytoplasm for a long time before being genetically expressed. Such complexes are called

Options

A. polysomes
B. ribonucleoprotein fibres
C. pro-oncogenes
D. informosomes

Answer

To answer the question regarding the complexes formed by eukaryotic mRNAs associated with proteins, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components**: Eukaryotic mRNAs (messenger RNAs) are essential molecules that carry genetic information from DNA to the ribosomes, where proteins are synthesized. In eukaryotic cells, these mRNAs are often associated with proteins.

2. **Formation of Ribonucleoprotein Complexes**: When mRNAs associate with proteins, they form ribonucleoprotein complexes. These complexes are crucial for the stability, transport, and translation of mRNA.

3. **Cytoplasmic Presence**: The question states that some of these ribonucleoprotein complexes can remain in the cytoplasm for an extended period before being expressed genetically. This means that they are not immediately translated into proteins.

4. **Identifying the Correct Term**: Among the options provided:
- Polyribosomes
- Ribonucleoprotein fibers
- Pro oncogenes
- Informosomes

We need to identify which term specifically refers to the ribonucleoprotein complexes that can persist in the cytoplasm.

5. **Correct Answer**: The term that describes these complexes is **polyribosomes** (also referred to as **polyzones**). These structures consist of multiple ribosomes translating a single mRNA strand and can remain in the cytoplasm for a significant time.

### Final Answer:
**Polyzones** (or **Polyribosomes**) are the correct answer.

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