If any protein encoding gene is expressed in a heterologus host, is called a........... .

Answer

**Step-by-Step Solution:**

1. **Understanding the Concept**: The question asks about the expression of a protein-encoding gene in a heterologous host. A heterologous host is an organism that is different from the one in which the gene is normally expressed.

2. **Identifying the Gene**: We start with a specific gene or DNA that encodes a protein. This gene is considered "foreign" because it originates from a different organism than the host.

3. **Using a Vector**: To express this foreign gene in the heterologous host, it is introduced into a vector, typically a plasmid. The plasmid serves as a vehicle to carry the foreign gene into the host organism.

4. **Transformation**: The plasmid containing the foreign gene is then transferred into the host organism. This process is known as transformation.

5. **Replication of the Vector**: The plasmid has the ability to replicate independently within the host. It does not integrate into the host's genome but instead replicates as an extrachromosomal element.

6. **Transcription and Translation**: Once inside the host, the foreign gene is transcribed into messenger RNA (mRNA), and then translated into a protein.

7. **Final Product**: The protein produced from this process is referred to as a "recombinant protein" because it is derived from a gene that has been recombined with the host's cellular machinery.

8. **Conclusion**: Therefore, if any protein-encoding gene is expressed in a heterologous host, it is called a **recombinant protein**.

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