1) Most phage's occur in 1 of 2 structural forms, having either cubic or helical symmetry. In overall appearance, cubic phage's are regular solids or polyhedral helical phage's are rod-shaped.
2) polyhedral phage's are icosahedral in shape. This means that the capsid has 20 facets, each of which is equilateral triangle, these facts come together to form the 12 corners.
3) In the simplest capsid there is a capsomere at each of 12 vertices, this capsomeres which is surrounded by 5 other capsomere is termed as penton.
4) In larger and more complex capsid the triangular facets are subdivided into a progressively larger number of equivalent triangle. thus a capsid may be composed of hundreds of camsomeres but it is still based on simplest on the simplest icosahedron model.
5) The elongated head of some tailed phage's are the derivatives of the icosahedral.
6) Rod- shaped viruses have there capsomeres arrange helically and not in staked ring.
7) Some bacteriophage's such as teven coliphages have very complex structure including a head and a tail. They are said to have binal symmetry because each virion has has both an icosahedral head and a hallow helical tail.
2) polyhedral phage's are icosahedral in shape. This means that the capsid has 20 facets, each of which is equilateral triangle, these facts come together to form the 12 corners.
3) In the simplest capsid there is a capsomere at each of 12 vertices, this capsomeres which is surrounded by 5 other capsomere is termed as penton.
4) In larger and more complex capsid the triangular facets are subdivided into a progressively larger number of equivalent triangle. thus a capsid may be composed of hundreds of camsomeres but it is still based on simplest on the simplest icosahedron model.
5) The elongated head of some tailed phage's are the derivatives of the icosahedral.
6) Rod- shaped viruses have there capsomeres arrange helically and not in staked ring.
7) Some bacteriophage's such as teven coliphages have very complex structure including a head and a tail. They are said to have binal symmetry because each virion has has both an icosahedral head and a hallow helical tail.
STRUCTURE OF ICOSAHEDRAL CAPSID
STRUCTURE OF HELICAL SHAPED VIRUSES (Tobacco mosaic virus)
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