Question

What is a plasmid?
a. Bacterial, linear, dsDNA
b. Extrachromosomal linear RNA
c. Extrachromosomal circular dsDNA
d. Autonomously replicating circular RNA

Answer 1

Hint: Plasmids are the extrachromosomal DNA that is separated from the actual DNA present in the cell, and it has the capability to replicate by itself, and it is mostly present in the cells of DNA, some of the members of archaea and eukaryotic organisms.

Complete answer:
- The plasmid is the circular DNA, where it is also called replicon because it has the capability to undergo replication autonomously.
- Plasmids usually carry from one bacteria to other bacteria with the help of conjugation and the DNA here present as double-stranded and circular.
- Based on the ability to conjugate, they are classified as conjugative and non-conjugative plasmids.
- Conjugative plasmids have transfer genes, and they promote conjugation, while non-conjugative plasmids transfer with the help of conjugative plasmids only.

Based on the function, plasmids are classified into the following types:
- Fertility plasmid(F plasmid): They contain transfer genes, and they are capable of conjugation and they may produce sex pili.
- Resistance plasmid( R plasmid): These are the plasmids, which are resistant to the antibiotics.
- Col plasmid: These are the plasmids that contain a gene that codes protein, and they can kill other plasmids.
- Degradative plasmid: These plasmids, are able to digest the unusual substances, ex: salicylic acid
- Virulence plasmid: This is the plasmid, which turns the normal bacteria into pathogens.

Hence, the correct answer is option (C).

Note: When coming to the uses, a plasmid is generally used for bacterial cloning, and it is also used for the protein production, And it is used for gene therapy in treatments of some diseases, and it is also used in genetic engineering in to reproduce some embryonic stem cells, etc.