The vector requires a…………, which helps in identifying selectively permitting the growth of transformants.

Options

A. selectable marker
B. cloning sites
C. antibiotic resistance gene
D. bacteriophage

Answer

To solve the question "The vector requires a…………, which helps in identifying selectively permitting the growth of transformants," we need to identify the correct term that fits in the blank. Let's break down the solution step by step:

### Step 1: Understand the Role of a Vector
A vector is a DNA molecule used to carry foreign genetic material into another cell. It can be a plasmid, bacteriophage, or cosmid. The primary function of a vector is to facilitate the transfer of this genetic material into host cells.

**Hint:** Remember that vectors are essential tools in genetic engineering for transferring DNA.

### Step 2: Identify Essential Features of a Vector
For a vector to function effectively, it must have certain features:
- **Origin of Replication (ORI):** This allows the vector to replicate independently within the host cell.
- **Selectable Marker:** This is crucial for identifying which cells have successfully taken up the vector containing the foreign DNA.

**Hint:** Think about what is needed to differentiate between cells that have incorporated the vector and those that have not.

### Step 3: Focus on Selectable Markers
Selectable markers are genes that provide a way to select for cells that have taken up the vector. They often confer resistance to antibiotics or allow for the identification of transformants through other means (like color change in blue-white screening).

**Hint:** Consider how researchers can determine which cells are successful in incorporating the desired DNA.

### Step 4: Evaluate the Options
Given the options:
1. Selectable Marker
2. Cloning Site
3. Antibiotic Resistance Gene
4. Bacteriophage

- **Selectable Marker:** Correct, as it helps in identifying transformants.
- **Cloning Site:** Incorrect, as it does not help in identifying transformants.
- **Antibiotic Resistance Gene:** While it can be a type of selectable marker, it is not a general term that encompasses all selectable markers.
- **Bacteriophage:** Irrelevant in this context, as it refers to a type of virus, not a feature of a vector.

**Hint:** Look for the term that broadly encompasses the ability to identify transformed cells.

### Step 5: Conclusion
The correct answer to fill in the blank is "selectable marker." This term accurately describes the feature of a vector that allows for the selective growth of transformants.

**Final Answer:** The vector requires a **selectable marker**, which helps in identifying selectively permitting the growth of transformants.