1
Obligatory intracellular parasites
Require living host cells to multiply,
• Contain DNA or RNA
• Contain a protein coat
• No ribosomes
• No ATP-generating mechanism
2
Host Range
• The spectrum of host cells a virus can infect
• Most viruses infect only specific types of cells in one host – Determined by specific host attachment sites and cellular factors
3
Bacteriophages
viruses that infect bacteria
• Range from 20 nm to 1000 nm in length
4
Virion
complete, fully developed viral particle
Nucleic acid—DNA or RNA can be single- or doublestranded; linear or circular
5
Capsid
protein coat made of capsomeres (subunits)
6
Envelope
lipid, protein, and carbohydrate coating on some viruses