Classification of Organisms

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Aroog Khan

Sue Bennett

Classification of Organisms

Unit 15.4

Task 1

Subgroups of virus, fungi and bacteria:

VIRUS - Viruses are very tiny, simple organisms. They cannot grow, metabolise or reproduce. Because they are tiny, they cannot be seen even by the naked eye. It cannot multiply on its own, so it has to invade a host cell.

Viruses cause many human infections, and are responsible for rare diseases. One of the rhinoviruses usually causes common colds.

Viruses may contain either DNA or RNA as their genetic material. RNA viruses have an enzyme called reverse transcriptase that permits the usual sequence of DNA-to-RNA to be reversed so the virus can make a DNA version of itself. RNA viruses include HIV and the hepatitis C virus. Viruses cause many serious human diseases, for instance ,  and .

The subgroups of a virus are:

  • Helical
  • Complex
  • Enveloped
  • Polyhedral

Helical capsids are made up of a single type of subunit, which is loaded around a middle axis to form a helical structure that might have an empty tube or central cavity. These results in filamentous virions or rod-shapes. These can be something from highly stiff and little, to lengthy and very flexible. The genetic material is bound into the protein helix by communications among the positive charges on the protein and negatively charged nucleic acid. The length of helical capsids is connected to the length of the nucleic acid contained within it and the diameter is responsible for the preparation of the proteomes and the size. An example of the helical virus is a tobacco mosaic virus. Helices are simple structures produced by piling repetitive components with a stable connection to one another as amplitude and pitch.

There are many a virus by which has a complex structure. Even though the common principles of symmetry explained are frequently used to construct part of the virus shell, the more complex and larger viruses cannot be only explained by a mathematical equation as can an icosahedron or a simple helix. For instance, the members of the poxvirus family show such group and the struggle of complexity. These viruses have brick shaped or oval particles. Actually, they are so big they were first looked at closely using high-resolution optical microscopes and thought at the time to be the spores of micrococci. The viral genetic information of the virus is kept in a protein-based membrane. The outer layer of this virus is an envelope made up of proteins and lipids.

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It is well known that the polyhedral virus was created in the viroplasma. It was produced after viral cell infection was included in the close developing membrane or in fascicles containing up to nine and was finally incapsulated in polyhedral protein. Polyhedral viruses are no enveloped viruses whose capsids make geometric shapes with flat edges and sides. Another way of making a virus capsid to organize protein subunits in the shape of hollow quasi-spherical structure is surrounding the genome within.

All influenza viruses have lipid envelopes, which consist of two sorts of spikes, neuraminidase (NA) and haemagglutinin (HA).There are ...

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