What is true plasmids ?

Options

A. Plasmids are widely used in gene transfer
B. These are found in both bacteria and viruses.
C. Plasmids contain genes for vital activates.
D. They are an important part of the chromosome .

Answer

**Step-by-Step Solution:**

1. **Understanding Plasmids:**
- Plasmids are small, circular, double-stranded DNA molecules that are separate from the chromosomal DNA in bacteria and some eukaryotic organisms. They are considered extra-chromosomal DNA because they exist independently of the main genetic material.

2. **Characteristics of Plasmids:**
- Plasmids can replicate independently of chromosomal DNA, which allows them to be passed on during cell division.
- They are most commonly found in bacteria and can also be present in some eukaryotic cells, but they are not found in viruses.

3. **Functions of Plasmids:**
- Plasmids often carry genes that provide advantages to the host organism, such as antibiotic resistance. This means they can contain genes that code for enzymes that inactivate antibiotics, helping bacteria survive in hostile environments.

4. **Evaluating the Statements:**
- **Statement 1:** "Plasmids are widely used in gene transfer." - This statement is true as plasmids are commonly used in genetic engineering to transfer genes between organisms.
- **Statement 2:** "They are found in both bacteria and viruses." - This statement is false because plasmids are not found in viruses.
- **Statement 3:** "Plasmids contain genes for vital activities." - This statement is misleading because while plasmids can carry beneficial genes, they do not contain essential genes necessary for the basic life processes of the organism.
- **Statement 4:** "They are an important part of the chromosomes." - This statement is false as plasmids are separate from chromosomal DNA.

5. **Conclusion:**
- The correct statement regarding plasmids is the first one: "Plasmids are widely used in gene transfer."