The Shape of a Virus

Viruses are so small of a size (20-750 nm) that most can only be seen through an scanning electron microscope.
Structure of a virus:

• genetic information molecule
• protein layer that envelopes the above molecule (capsid)
• Inside there are nucleic acids that form either RNA/DNA.

There are 4 known virus shapes:

1. Helical
2. Icosahedral 
3. Envelope
4. or a combination called complex

------------------------------------------------------------------------------------------------------------The helical shaped virus has protein organized in a circular path. This forms a tube with a hollow core that holds nucleic acid. 

Width: 15-19 nm

Length: 300-500 nm

virus known to have this shape: filamentous virus ex. tobacco mosaic virus

filamentous virus usually infect gram negative bacteria.

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The icosahedral shaped virus has a sphere-like shaped made from fused equilateral triangles. These triangles are "identical protein sub units". This prime shape holds the genetic material within. Virus's with this shape tend to be released when a cell lyses. 

amount of protein sub-units: 20 faces

size: 70-90 nm

know viruses with this shape: polio virus, rhinovirus, and adenovirus

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The envelope shaped virus is a standard helical/isocahedral virus except it is encased in a lipid bilayer membrane.These membranes come from the host cell. 

known viruses of this type: hepatitis C, HIV, and influenza virus.

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Complex type of virus have a head and tail they also only infect bacteria. The tail creates a hole in cell wall of caught bacteria then releases DNA into it. These complex viruses are among the largest. Also known as bacteriophage

Examples of this type: smallpox virus(variola).

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https://youtu.be/CBMr142ynbk

https://youtu.be/Ofd_lgEymto

https://dr282zn36sxxg.cloudfront.net/datastreams/f-d%3A0af319c1f63d9f6a49d9b6245463fc8fea256fd364c6a8e427999d1d%2BIMAGE_THUMB_POSTCARD_TINY%2BIMAGE_THUMB_POSTCARD_TINY.1

http://figures.boundless-cdn.com/14011/raw/tevenphage.svg

https://upload.wikimedia.org/wikipedia/commons/f/f0/Lipid_bilayer_section.gif

https://youtu.be/_HvKxgihn4I

http://images.slideplayer.com/34/8309974/slides/slide_6.jpg

https://morgridge.org/wp-content/uploads/Virus-Structure.pdf

http://www.twiv.tv/wp-content/uploads/2009/07/helical-symmetry2-1024x775.jpg