Viruses Structure

Virus outer shell have function to protect fragile nucleic acid genome from physical damage, chemical damage and enzymatic damage. The protein subunits in a virus capsid are multiply redundant, it mean that if the damage to one or more subunits may render that particular subunit non-functional, but does not destroy the infectivity of the whole particle.

The outer of viruses surface is responsible for recognition of the host cell. It takes the form of binding of a specific virus attachment protein to a cellular receptor molecule. While capsid has a role to play in initiating infection by delivering the genome from its protective shell which can interact with the host cell.

After some experiment to purified of tobacoo mosaic virus (TMV) RNA and coat protein were incubated together, virus particle formed. Virus particles could form spontaneously from purified subunits without any extraneous information indicated that the particle was in the free energy minimum state.

Tobacco mosaic virus is representative of one of two major structural classes seen in viruses of all types with helical symmetry. The simple way to arrange multiple, identical protein subunits is to use rotational symmetry and to arrange the irregularly shaped protein around the circumference of a circle to form a disc.