Define the term virus and identify what organisms viruses ca

Define the term virus, and identify what organisms viruses can infect. What are the anatomical features of a typical virus? Describe the different shapes of viruses. Compare and contrast enveloped and naked viruses. and explain the life cycles of lytic and lysogenic viruses.

Solution

A virus is a type of microorganism smaller than bacterium which can grow only with the help of living host cell. The virus cannot live individually , as they will use host cell machinary to grow themselves. The virus can infect all types of living organisms like human, animals, birds, bacteria etc.

A typical viral structure contains three major parts. One is the nucleic acid, which may be either DNA or RNA but not both, which will act as genetic material. Another part is that a capsid which envelops the nucleic acid as a protein coat. Some viruses has additional envelope made up of glycoproteins which can protects nucleocapsid.

Based on the presence of outer envelope viruses are classified in to two: enveloped and non enveloped or naked viruses. Charecteristics of naked virus includes: they are more virulent, resistant to heat, acids, and drying. They can survive inside gastrointestinal tract. Their outermost layer is capsid madeup of proteins. They can induce antibody production in host.

The charecteristics of enveloped virus includes: They are less virulent than naked virus. They are sensitive to heat, acids and drying. They cannot survive inside gastrointestinal tract. Their outermost layer is madeup of glycoproteins. They will induce both cellmediated and antibody mediated immune response in host.