Viruses: Nature and Characteristics

Viruses that use RNA as their genetic material.

Viruses that use DNA as their genetic material.

Viruses that infect bacteria. They are a type of DNA virus.

A virus that infects plants and causes diseases like mosaic viruses.

A virus that causes infections in animals.

The rod-shaped structure of certain viruses like Tobacco Mosaic Virus.

Viruses with a spherical shape, like Polio and HIV.

Viruses with a cubical shape, like Herpes.

Viruses that lack an outer membrane, like TMV and T₂ virus.

Viruses with an outer membrane, like Influenza and HIV.

Viruses are obligate intracellular parasites, meaning they can only reproduce inside a host cell. They lack the cellular structure of bacteria and are too small to be seen with a light microscope.

A protein coat that encases and protects the viral nucleic acid. It's the outer layer of the virus.

The core of a virus, containing either DNA or RNA. It carries the genetic information needed for viral replication.

The process by which viruses replicate inside a host cell, using the host's resources to create more viruses.

A bacteriophage is a type of virus that specifically infects bacteria.

They are too small to be seen with a light microscope, and require the use of an electron microscope.

The first time a virus-borne disease was noticed, Edward Jenner observed smallpox in 1796.

The discovery of the AIDS virus, a significant milestone in virology, occurred in 1984.

Viruses are acellular, meaning they lack a cell membrane, cytoplasm, ribosomes, and other cellular structures.

Viruses lack metabolic enzymes, so they cannot perform metabolic processes like respiration or nutrient breakdown. They rely on host cells for these functions.

Viruses are unable to reproduce independently. They require a host cell to replicate their genetic material and produce new viruses.

Viral capsids are protein shells that surround the viral nucleic acid (DNA or RNA). These shells are composed of protein subunits called capsomeres.

The arrangement of capsomeres in a viral capsid determines the shape and size of the virus. This structure can be either helical (rod-like) or polyhedral (round).

Viruses can be classified into different categories based on factors like their genetic material (DNA or RNA), capsid morphology, and the type of host they infect.

Some viruses have an outer envelope composed of lipids, lipoproteins, or carbohydrates. This envelope helps the virus to enter and exit host cells.

Viral nucleic acid, either DNA or RNA, is the core component of a virus. It carries the genetic information for replicating the virus.

Viral proteins are essential for the virus's survival and replication. They can act as antigens, triggering immune responses in the host, or as enzymes involved in viral replication.

Changes in the genetic material (mutation) or the arrangement of proteins (variation) can occur in viruses, leading to evolution and adaptation.