What is the structure of helical virus?
What is the structure of helical virus?
Helical. This virus structure has a capsid with a central cavity or hollow tube that is made by proteins arranged in a circular fashion, creating a disc like shape. The disc shapes are attached helically (like a toy slinky) creating a tube with room for the nucleic acid in the middle.
What do viral capsids contain?
A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres.
What is the chemical composition of virus capsomers?
Each capsomer is composed of one to six molecules of polypeptide, usually of the same kind (homopolymers) but sometimes different (heteropolymers). Capsomers from the vertices and the faces are usually composed of different polypeptides.
What is helical capsid?
Helical capsids are made up of a single type of protein subunit stacked around a central axis to form a helical structure. The helix may have a hollow center, which makes it look like a hollow tube. This arrangement results in rod-shaped or filamentous virions.
What are the structural components of a virus?
All viruses contain nucleic acid, either DNA or RNA (but not both), and a protein coat, which encases the nucleic acid. Some viruses are also enclosed by an envelope of fat and protein molecules. In its infective form, outside the cell, a virus particle is called a virion.
What is helical symmetry?
Helical (spiral) symmetry: The capsomere and nucleic acid are wined together to form helical or spiral tube like structure. Most of the helical viruses are enveloped and all are RNA viruses.
What is a helical capsid?
What is the difference between protomers and capsomeres?
The key difference between protomers and capsomeres is that protomers are structural units of oligomeric proteins while capsomeres are individual proteins composed of protomers, which are structural subunits of the viral capsid. A virus is an intracellular obligate parasite, which is an infectious particle.
What are examples of helical capsids?
Past Systems of Classification
| Virus Classification by Capsid Structure | |
|---|---|
| Capsid Classification | Examples |
| Enveloped icosahedral | Epstein-Barr virus, herpes simplex virus, rubella virus, yellow fever virus, HIV-1 |
| Enveloped helical | Influenza viruses, mumps virus, measles virus, rabies virus |
| Naked helical | Tobacco mosaic virus |
What is the difference between helical and icosahedral viruses?
A helical virus is a virus that has a capsid shaped in a filamentous or rod-shaped structure that has a central cavity that encloses its nucleic acid. An icosahedral virus is a virus consisting of identical subunits that make up equilateral triangles that are in turn arranged in a symmetrical fashion.