Question

What are plasmids? Mention any two features of an ideal plasmid.

Answer 1

The extra chromosomal regions of DNA are called plasmids. They are self replicating and are dependent on the host for replication. They are used in recombinant DNA technology.

Complete answer:
To answer the question we must know about the plasmids and their uses.
Recombinant DNA technology is joining desired DNA fragments into a host organism using a vector called the plasmids. Plasmids are the vectors which are a circular DNA molecule. They have restriction sites which can be recognised by the restriction enzymes. These strands of DNA are separated from the main DNA. It is most commonly found in bacteria.

The plasmids carry genes which are resistant to antibiotics. This is an added advantage for an organism. Plasmids carry very small amounts of genes which are suitable for certain conditions. Plasmids are capable of replicating independently within a host. Plasmids are transmitted from one organism to another by conjugation.
Features of an Ideal plasmid-
->It is small in size
->It is capable of self replicating and produces multiple copies in a cell. It makes it a useful tool in the cloning process.
->It has multiple cloning sites.
->It has genes for antibiotic resistance.

Additional Information: Human beings have plasmid DNA inside the Mitochondria. It does not carry similar 23 pairs of chromosomes.

Note: The term plasmid was discovered in 1952 by molecular biologist Joshua Lederberg and he referred to it as any extrachromosomal hereditary determinant. The most commonly used plasmid vector in Recombinant DNA Technology is E.Coli plasmid.