Gene library or DNA library has collection of

Options

A. DNA and RNA
B. Any one type of gene of Organism
C. c DNA only
D. All possible genes of all organisms

Answer

To solve the question regarding what a gene library or DNA library contains, we can break it down step by step:

### Step-by-Step Solution:

1. **Understanding Gene Library and DNA Library**:
- A gene library (or DNA library) is a collection of DNA fragments that represent the genetic material of an organism. It serves as a resource for genetic research and manipulation.

**Hint**: A gene library is essentially a repository of DNA fragments from organisms.

2. **Types of DNA in Gene Libraries**:
- Gene libraries can contain various types of DNA, including genomic DNA and complementary DNA (cDNA). cDNA is synthesized from mRNA and represents the expressed genes in a cell.

**Hint**: Focus on the types of DNA that are typically included in a gene library.

3. **Purpose of a Gene Library**:
- The main purpose of a gene library is to isolate specific genes of interest for further study or manipulation. This means that it is not limited to just one type of gene or a single organism's genes.

**Hint**: Consider the functionality of a gene library in terms of gene isolation.

4. **Evaluating the Options**:
- **Option 1**: DNA and RNA - This is incorrect as gene libraries primarily focus on DNA.
- **Option 2**: Any one type of gene of an organism - This is incorrect since gene libraries contain a variety of genes, not just one type.
- **Option 3**: cDNA only - This is partially correct but too restrictive, as gene libraries can contain more than just cDNA.
- **Option 4**: All possible genes of all organisms - This is also incorrect as it suggests an unrealistic scope for a gene library.

5. **Correct Answer**:
- The most accurate description of what a gene library contains is that it includes a comprehensive collection of DNA fragments, primarily cDNA, but not limited to just cDNA or any one type of gene.

**Final Answer**: The correct answer is option 3, which refers to cDNA, as it is a significant component of gene libraries.