Question

Cosmid is
A. Extra DNA in Bacteria
B. Fragment of DNA inserted in bacteria for forming copies
C. Circular DNA in bacteria
D. Extragenetic material in Mycoplasma

Answer 1

Cosmid is a hybrid of plasmid as well as lambda phage cos sequence. These are the DNA sequences used as a cloning vector in genetic engineering. They are considered as an extra DNA in bacteria which is inserted in bacteria along with DNA to produce more copies of gene therapy.

Complete answer:
Option – A – A plasmid is a ring-shaped part of DNA that is found within the bacterial cells. Plasmids replicate independently of the chromosomal DNA which is present in the nucleoid but they are always copied into the next generation cells. Plasmids often include genes that give bacteria genetic advantages like antibiotic resistance.
Option – B – In order to get the DNA fragment into a bacterial cell in a way that it will be copied or expressed, the fragment is first inserted into a plasmid. A plasmid also known as vector which is a small circular DNA molecule.
Option – C – A plasmid is a small, extrachromosomal DNA molecule present within a cell that is physically separated from chromosomal as well as it can replicate by itself. They are most found as small circular, double-stranded DNA molecules in bacteria.
Option – D – Mycoplasma is plural mycoplasmas that is a genus of bacteria lacking a cell wall around their cell membranes. This characteristic makes them naturally resistant to antibiotics that are target cell wall synthesis.

Hence, the correct answer to this question is option - A. “Extra DNA in bacteria".

Note: A cosmid is a form of hybrid plasmid that includes a Lambda phage cos sequence. Cosmids DNA sequences are originally from the lambda phage.