Question

A single stranded DNA is present in which of the following organisms?
A. TMV
B. Salmonella
C. Coliphage $$\varphi \times 174$$
D. Bacteria.

Answer 1

Hint:Single stranded DNA is found in the bacteriophages. The single stranded DNA in these viruses is a cyclic molecule.

Complete Answer:
To answer this question, first, we need to know about the single strand DNA. A DNA molecule containing only a single strand opposite to the common two strands of nucleotides in helical shape. In nature, single stranded DNA genome is present in Parvoviridae. Single stranded DNA can also be obtained synthetically by constant cooling of heat-denatured DNA. Heating can result in the strands to separate whilst constant cooling stops them from renaturation. Single stranded DNA extracted from the phages is utilized for sequencing, site-directed mutagenesis, or as a sequence-specific probe etc.
Now, let us find the solution from the option.
A single-stranded DNA is present in Coliphage 174. The $$\varphi \times 174$$ bacteriophage was the first DNA based genome to be sequenced. This bacteriophage has around a single-stranded DNA genome of 5386 nucleotides that code 11 proteins. Only 8 are important to viral morphogenesis out of those 11 proteins.

Thus, the correct option is C. i.e. Coliphage $$\varphi \times 174$$ .

Note:Only a few human and animal pathogenic viruses are known that have a single-stranded DNA genome. The individuals of the Parvoviridae family have a straight genome, on the other hand, the genome of the individuals of the Circoviridae family and also the newly developed family Anelloviridae has a round shaped genome.