The vectors used in eukaryotic cells are constructed such that they can exist in both the eukaryotic cells and E. coli are called :

Options

A. Shuttle vectors
B. pBR322
C. Yeast artificial chromosome
D. Bacterial artificial chromosome

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about vectors that can exist in both eukaryotic cells and E. coli. We need to identify the specific term used for such vectors.

2. **Defining Vectors**: Vectors are DNA molecules used to carry foreign genetic material into another cell. They are essential tools in biotechnology for gene cloning and expression.

3. **Types of Vectors**: There are various types of vectors, including plasmids, cosmids, and artificial chromosomes. However, not all vectors can function in both eukaryotic cells and prokaryotic cells like E. coli.

4. **Identifying Shuttle Vectors**: A shuttle vector is a type of vector that is designed to replicate in two different host organisms. In this case, it can exist in both eukaryotic cells (like yeast or mammalian cells) and prokaryotic cells (like E. coli).

5. **Features of Shuttle Vectors**: Shuttle vectors typically contain:
- **Origin of Replication**: This allows the vector to replicate in both host types.
- **Selectable Markers**: These help in identifying cells that have successfully taken up the vector.
- **Multiple Cloning Sites**: These allow for the insertion of foreign DNA.

6. **Conclusion**: Based on the definition and characteristics of shuttle vectors, the answer to the question is that the vectors used in eukaryotic cells that can also exist in E. coli are called **shuttle vectors**.

**Final Answer**: Shuttle vector.

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