Question

Extrachromosomal DNA of bacteria is
A) Mesosome
B) Microsome
C) Plasmid
D) Chromosome

Answer 1

Hint: Extrachromosomal DNA is the DNA that is found off the chromosomes, that can be inside or outside of the nucleus of a cell. Most DNA in an individual genome is found in the chromosome of the nucleus.

Complete Answer:
- A plasmid of bacterial origin is an extrachromosomal circular DNA present freely inside the cytoplasm of bacteria. It contains DNA as genetic material.
- Sometimes, it is also present in archaea and eukaryotic organisms. It can replicate independently. It usually contains certain specific genes that provide added advantage to the bacteria-containing it.
For example, it contains antibiotic-resistant genes.

Now consider the options provided in the question,
A) Mesosome: A specialized membraneous structure is a mesosome that is formed by an extension of the plasma membrane into the cell. These extensions are in the form of vesicles, tubules, and lamellae.
B) Microsome: Microsomes are structured like vesicles that artifacts are rebuilt from pieces of the endoplasmic reticulum when eukaryotic cells are breakdown inside the laboratory. Microsomes are not ordinarily present in living cells.
C) Plasmid: A plasmid is a small, circular DNA molecule that is different from the cell’s chromosomal DNA. It can replicate independently of the chromosomal DNA and are found in most of the bacteria. Thus, the correct answer is 'Plasmid.'
D) Chromosome: Chromosome is highly condensed, coiled chromatin fiber. Each chromosome is made up of protein and a single DNA molecule.

Note: In bacteria, Episomes are a group of extrachromosomal genetic elements called plasmids consisting of DNA.