Viruses

Virus

Microscopic particles that infect cells of other organisms.

How do viruses differ from other microorganisms?

• They are obligate intracellular parasites capable of Infecting both eukaryotic and prokaryotic organism with their genetic material.

• They lack the biochemical machinery necessary for replication.

Bacteriophage

A virus that infects bacteria

Virus classification is based on:

• Morphology

• Nucleic acid type

• Mode of replication

• Host organisms

• The type of disease they cause

How does The International committee on Taxonomy of Viruses classify viruses?

Based on their shared genetic and structural properties.

• Kingdom

• Class

• Order

• Family

• Genus

• Species

What properties determine the order of a virus?

• The type of nucleic acid, DNA or RNA, single or double stranded

• The presence or absence of an envelope

How does the Baltimore classification system classify viruses?

Based on the relationship between the viral genome and the mRNA.

What are the groups of the Baltimore class system?

1. Double stranded DNA (dsDNA) viruses

2. Single stranded DNA (ssDNA) viruses

3. Double-stranded RNA (dsRNA) viruses

4. Positive-sense single stranded RNA [(+s) ssRNA] viruses

5. Negative-sense single stranded RNA [(-s) ssRNA] viruses

6. Reverse-transcribing diploid single-stranded RNA (ssRNA-RT) viruses

7. Reverse-transcribing diploid double-stranded RNA (dsRNA-RT) viruses

Virus morphology

The study of the virus's shape, size, and structural components, including its genetic material (nucleic acid) and protein coat (capsid).

• Vary in size, generally ranging from about 20 to 400 nanometers in diameter.

What