Episomes were discovered by Jacob and Wollman (1960). These represent

Options

A. extrachromosomal segment that is temporarily attached with main nucleoid
B. extrachromosomal genetic material independent of main nucleoid
C. viruses
D. archaebacteria

Answer

### Step-by-Step Text Solution:

1. **Understanding the Discovery**: The question states that episomes were discovered by Jacob and Wollman in 1960. It is important to recognize the significance of this discovery in the field of genetics.

2. **Definition of Episomes**: Episomes are genetic elements that can replicate independently of chromosomal DNA. They are essentially a type of plasmid that can integrate into the chromosome of a host cell.

3. **Replication Mechanism**: Episomes can replicate in two ways:
- **Autonomously**: This means they can replicate independently, without the need to be integrated into the host chromosome.
- **In Association with Chromosomes**: Episomes can also integrate into the host chromosome, allowing them to replicate along with the chromosomal DNA.

4. **Presence in Organisms**: Episomes are found in both prokaryotic (like bacteria) and eukaryotic (like yeast and plants) organisms. This indicates their versatility and importance in various biological systems.

5. **Conclusion**: Based on the above points, we can conclude that episomes represent extra chromosomal genetic elements that can integrate into the main nucleoid and replicate either independently or in association with the chromosome.

### Final Answer:
Episomes represent extra chromosomal genetic elements that can replicate autonomously or in association with chromosomes.

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