how are viruses structured?

The viruses do not have a cellular structure. For this reason, it does not contain organelles, ribosomes and cell membranes in cells. A virus; a nucleic acid center, a capsid from a protective layer in the outer protein structure, or a protein envelope or a phospholipid envelope derived from the inner cell. Capsid is a protein consisting of subunits named capsomer.

In addition, viruses may contain additional proteins such as enzymes. The most obvious difference between members of viral families is that morphology (morphology) and morphology are quite different from each other. Interestingly, there is no connection between the complexity of the structure of the viruses and the structural properties of the host cell they infect. For example, although the virus bacteriophage has a very complex structure, the bacteria that are the host cells of this virus are simple.
Viruses are a large number of shapes and sizes. Generally, viruses are divided into four groups by shape. These groups are; filamentary, isometric, enveloped and contains head and tail. Filamentous viruses are long and cylindrical. Most plant viruses, including tobacco mosaic virus, are filamentous. Isometric viruses are globular and poliovirus and herpes viruses are in this class. Enveloped viruses also have membranes around their capsids, and animal viruses such as HIV are enveloped. Those that contain head and tail structure infect bacteria.


Most viruses use some form of glycoprotein to bind to the host cell. This binding is necessary for the virus to transfer the genetic material to the cell. The molecule used to bind the virus binds to a receptor on the cell surface.

The presence or absence of a virus envelope can give us clues as to which disease the virus is causing and which types of cells it infects. For example; adenoviruses are enveloped animal viruses and cause respiratory tract diseases in humans. Other enveloped viruses; poliovirus, papilloma virus, and hepatitis A.

Enveloped viruses such as HIV, which cause AIDS, include nucleic acids and capsid proteins. The envelope around the capsid consists of a phospholipid layer and proteins. The glycoproteins in the viral envelope are used to bind to the host cell. It is responsible for keeping the envelope structure stable in other proteins in the envelope. Due to the fragility of the envelope structure, envelope-free viruses are more resistant to temperature and pH changes.
Genetic Material of Viruses

All organisms use DNA as genetic material, but viruses can contain DNA or RNA. The virus genome is small and contains only genes that encode proteins that are not available from the host organism. The genetic material in viruses can be single or double-stranded. It can also be linear or circular in shape. While most viruses contain a single nucleic acid, other viruses have several nucleic acids called segments
Viruses containing DNA utilize the mechanisms of host cells to copy their DNA and to synthesize viral proteins from DNA. DNA viruses that cause disease in humans; chickenpox, hepatitis B and herpes viruses that cause warts in the genital area.
Viruses carrying RNA as a genetic material also replicate themselves in the host cell and place their genomes in the host cell genome. To do this, it encodes an enzyme that converts RNA into DNA, and this DNA molecule integrates into the host cell genome. Such viruses are called retroviruses. Some of the human diseases caused by RNA viruses are; rabies, measles and hepatitis C.
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