1. Viruses↔Obligate intracellular parasites; can affect all cell types including bacteria; few
archaeal viruses; theyre either DNA or RNA not both. single or double stranded
1. Capsid↔surrounds the nucleic acid; protein subunits arranged in a repetitive
pattern; protomers
1. protomers↔each subunit of the protein in the capsid; they self assemble;
thousands of protomers assemble to form capsid.
2. nucleocapsid↔capsid+genome ; they are the simplest virions
3. Viral genome
viruses affecting cellular organisms and most bacterial and DNA→dsDNA
most plants→ssRNA (most RNA viruses are ss)
1.viruses have varied genomes→ssRNA,ssDNA, dsRNA, DNA viruses are
dsDNA,
2. segmented genomes→(usually RNA) in RNA viral genomes like
influenza; consists of multiple segments of RNA they are smaller than
most of that of other cells.
2. virion↔extracellular viruses; inactive because they posses few enzymes and
cannot reproduce outside living cells.
3. viruses as nucleic acids→intracellular viruses that exists as nucleic acids; at some
point will use host cells to synthesize viral components.
4. bacteriophages or phages→viruses that affect bacteria.
2.
3.
4.
5. Viral structure
o 2 main types of capsid symmetry
,
Helical symmetry→length and width determined by the size of
its protomers and viral genome, nucleic acid- because the length of the
helical capsid never extends much beyond the end of the viral genome .
shaped like hollow tubes with protein walls. Tobacco mosaic virus(TMV)
have a ridgid helical capsidstructure, whereas some like influenza
virus have flexible helical capsid.
Spherical/ icosahedral symmetry→most efficient enclosed structure;
icosahedron→a regular polyhedron with 20 equilateral triangular
faces and 12 vertices
capsomers→composed of ring or knob shaped assemblages of 5
protomers called pentamers(pentons) or hexamers.
pentamers→capsomers composed of 5 protomers, are
usually at the vertices of the icosahedron.
hexamers(hexon)→capsomers that possess 6
protomers; generally from icosahedrons edges
and triangular faces of capsid. Some icosahedrons are
formed only by hexamers.
1. Envelope→derived from the membranes of the host cell thus the envelope
lipids and carbohyates are acquired from the host; but also contains viral
coded proteins
archaeal viruses; theyre either DNA or RNA not both. single or double stranded
1. Capsid↔surrounds the nucleic acid; protein subunits arranged in a repetitive
pattern; protomers
1. protomers↔each subunit of the protein in the capsid; they self assemble;
thousands of protomers assemble to form capsid.
2. nucleocapsid↔capsid+genome ; they are the simplest virions
3. Viral genome
viruses affecting cellular organisms and most bacterial and DNA→dsDNA
most plants→ssRNA (most RNA viruses are ss)
1.viruses have varied genomes→ssRNA,ssDNA, dsRNA, DNA viruses are
dsDNA,
2. segmented genomes→(usually RNA) in RNA viral genomes like
influenza; consists of multiple segments of RNA they are smaller than
most of that of other cells.
2. virion↔extracellular viruses; inactive because they posses few enzymes and
cannot reproduce outside living cells.
3. viruses as nucleic acids→intracellular viruses that exists as nucleic acids; at some
point will use host cells to synthesize viral components.
4. bacteriophages or phages→viruses that affect bacteria.
2.
3.
4.
5. Viral structure
o 2 main types of capsid symmetry
,
Helical symmetry→length and width determined by the size of
its protomers and viral genome, nucleic acid- because the length of the
helical capsid never extends much beyond the end of the viral genome .
shaped like hollow tubes with protein walls. Tobacco mosaic virus(TMV)
have a ridgid helical capsidstructure, whereas some like influenza
virus have flexible helical capsid.
Spherical/ icosahedral symmetry→most efficient enclosed structure;
icosahedron→a regular polyhedron with 20 equilateral triangular
faces and 12 vertices
capsomers→composed of ring or knob shaped assemblages of 5
protomers called pentamers(pentons) or hexamers.
pentamers→capsomers composed of 5 protomers, are
usually at the vertices of the icosahedron.
hexamers(hexon)→capsomers that possess 6
protomers; generally from icosahedrons edges
and triangular faces of capsid. Some icosahedrons are
formed only by hexamers.
1. Envelope→derived from the membranes of the host cell thus the envelope
lipids and carbohyates are acquired from the host; but also contains viral
coded proteins
