Morphology & Taxonomy

• any of a large group of submicroscopic infectious agents

• nonliving extremely complex molecules

• typically contain a protein coat surrounding an RNA or DNA

• no semipermeable membrane

• capable of growth and multiplication only in living cells

• The vast majority of viruses are not pathogenic to humans, and many play integral roles in propping up ecosystems.

• Others maintain the health of individual organisms – everything from fungi and plants to insects and humans

• non pathogenic viruses

• do not know how many viruses even exist.

• If viruses suddenly disappeared, some bacterial populations would likely explode; others might be outcompeted and stop growing completely.

  This would be especially problematic in the ocean, where more than 90% of all living material, by weight, is microbial. Those microbes produce about half the oxygen on the planet – a process enabled by viruses.

1.Nature of the nucleic acid in the virion

2.Symmetry of the protein shell

3.Presence or absence of a lipid membrane

4.Dimensions of the virion and capsid

morphology is the study of the shapes and arrangement of parts of organisms

• the cells and tissues of a host which support growth of a

  particular virus or bacteria.

• e.g. some viruses have a broad tissue tropism and can infect many types of cells and tissues. Other viruses may infect primarily a single tissue or cell type.

pitch is height of one helix turn

Number of structural units per face