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non-living characteristics of the virus

Viruses are highly contagious Obligate parasites. Viruses are the major cause of the number of diseases and deaths worldwide. Their core genome is made up of only one nucleic acid (DNA or RNA). Which is protected inside a protein shell (capsid). In addition, some viruses have lipoprotein membranes outside the capsid called Envelop. It protects the virus.

Structure of virus -             Genome -            Capsid -               Envelope

The virus can remain active only inside the host. Therefore, they are also called obligate parasites. Without the host, it remains dormant for a long time and becomes active as soon as it enters the host cell.

The virus is so small that it can also grow inside the bacteria.

It cannot replicate in the inactive state. To replicate its growth inside the host cell, it replicates its DNA and RNA using the energy of the host cell. It uses the host cell's protein synthesis mechanism in its growth. Which grows rapidly.

Protein synthesis is the process in which a cell protein is formed, which is in stage 2.

1 - Transcription and 2 - Translation)

The virus also creates a new viral particle inside the host cell in addition to the replicator. In this way, it also affects other cells. Therefore it is very difficult to make antiviral medicines.

The negative staining method revealed that viruses fall into the 3 main groups.
  1. Cubic
  2. Helical,
  3. Complex.

Cubic viruses example is adenovirus (a respiratory disease in man), herpes virus ( cold sores in man), polyomavirus (tumors in rodents, cancer in a man).

Helical plant virus, tobacco mosaic virus (TMV). viruses of mumps, new cattle disease.

Complex virus examples are large bacterial viruses, cowpox.

Types of viruses:

The virus can be divided mainly into 2 fragments.
1- DNA virus,
2 - RNA virus.

DNA virus:

  • Adenoviruses,
  • Hepadnaviruses
  • Herpesviruses
  • Papillomaviruses
  • Poxviruses

RNA Virus:

  • Picornaviruses,
  • Orthomyxoviruses,
  • Paramyxoviruses,
  • Rhabdoviruses
  • Arboviruses,
  • Rotavirus
  • Retrovirus.

Properties of viruses:

  • they are not free-living,
  • they have only a single kind of nucleic acid (DNA or RNA), never both,
  • the outer shell mainly of protein,
  • they active only living culture media,
  • they have no metabolic enzymes or protein synthesis machinery of their own.
  • it uses host machinery for their protein synthesis.
  • they replicate and do not grow, but their nucleic acid directs the host cell to make various parts of the virus and then to assemble these parts into complete particle virions.

the size of viruses size range between 10 and 200 nm. the size of yellow-fever, poliomyelitis is the diameter of about 25 nm. and The size of the smallpox virus is a diameter of 250 nm.

the shape of viruses has differed widely. rod-shaped, rounded, some virus is bullet-shaped.

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