Question

Which of the following types of molecule is NOT present as part of a retroviral virion?

Select one:

a. DNA

b. RNA

c. protein

d. lipid

e. glycoprotein

Answer 1

Virion is the extracellular infectious virus particle. The virion consists of outer nucleoprotein capsid and inner nucleic acid core. Retroviruses are enveloped, spherical viruses that are released by budding through the host cell membrane. Example of retrovirus is HIV (Human Immunodeficiency Virus).

Virion:-

Envelope: HIV is a spherical enveloped virus. The nucleocapsid has an outer icosahedral shell and an inner core enclosing ribonucleoproteins.

Genome:- the genome is composed of two identical single stranded positive sense RNA copies with the reverse transcriptase enzyme (characteristic feature of retroviruses).

Lipoprotein envelope:- the lipoprotein envelope consists of lipid derived from the host cell membrane and glycoproteins coded by the virus. These glycoproteins areprojecting knob like spikes on the surface and the anchoring transmembrane pedicles.

The retrovirus virion does not contain DNA because it has enzyme (protein) called reverse transcriptase which will transcribe the DNA whenever it infects the cell.

Answer is DNA.