What does quasi equivalent mean?

Quick Reference. A term that describes the subunit packing in a quasi-crystalline array, e.g. a virus coat where there is some strain but the overall structure is very stable.

Are all viruses icosahedral?

The majority of viruses can be categorized as having helical or icosahedral structure. A few viruses, however, have a complex architecture that does not strictly conform to a simple helical or icosahedral shape. Poxviruses, geminiviruses, and many bacteriophages are examples of viruses with complex structure (Fig.

What are capsids made from?

The capsid surrounds the virus and is composed of a finite number of protein subunits known as capsomeres, which usually associate with, or are found close to, the virion nucleic acid.

What are icosahedral viruses?

Icosahedral. These viruses appear spherical in shape, but a closer look actually reveals they are icosahedral. The icosahedron is made up of equilateral triangles fused together in a spherical shape. This is the most optimal way of forming a closed shell using identical protein sub-units.

What is quasi official?

adj denoting or relating to powers and functions similar to those of a judge, such as those exercised by an arbitrator, administrative tribunal, etc.

What are the characteristics of viral capsids?

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.

Where is capsid formed?

Most viruses capsid spontaneously self-assembles around the viral genome in the cytoplasm, thus linking the assembly and packaging process. Helical capsids are assembled around genomic RNA or DNA, and rely on self and nucleic acid interactions to assemble. Assembly and packaging are linked.

Is TMV a helical virus?

Helical viruses are typified by the tobacco mosaic virus (TMV) which was one of the first viruses to be understood at a structural level. The capsid of this RNA-containing virus is comprised of 2130 subunits of a single structural protein consisting of 157 amino acids with a molecular weight = 17,400.