Viruses are microscopic biological agents that reproduce within living cell tissue. They depend on living cells for survival and replication. Some viruses infect humans, while others infect bacteria and plants. A virus is composed of two parts, one outside the host cell and the other inside it. The virion is the virus’ outer part. The virion is responsible for carrying the virus’ genetic information throughout the host cell.
Viruses, eukaryotic organisms with complex morphologies, have the ability to attach themselves to their hosts. They are surrounded by a membrane called a capsomere. Their outer layer consists of small protein subunits called capsids. Each virus contains DNA, which is its genetic material, and glycoproteins to attach to its host cell. In addition, a virus may contain a phospholipid envelope, which helps it attach to its host cell.
Viruses use cell membranes to replicate. The virus develops and bursts from its host cell, releasing progeny viruses into the surrounding environment. These progeny virus infect new cells. The resulting infection is a viral disease. These events trigger the body’s immune system, and the immune response to the viral infection is by creating symptoms.
Viruses differ from bacteria in their size and structure. Viral particles vary in size from twenty to four hundred nanometers in diameter. Bacteria are about 100 times larger than viruses. Because viruses are so small, they can be observed only under a microscope. Viruses, however, cannot be seen with the naked eye. Large virions, such as those of the poxvirus family, can be seen under a light microscope.
Most viral species are RNA. The genome of an RNA virus is a blueprint for its proteins. To synthesize virus proteins, the host’s ribosomes will read this RNA. Some viruses even contain a gene for synthesizing missing proteins. The complement to the viral genome is created by the host cell, dsDNA. These viral proteins then get synthesized and are expressed. These viral proteins are then synthesized and expressed.
Viruses can infect plants and bacteria. Many viruses only affect a particular species of bacteria or plant. Others viruses are more widespread. These viruses include the cucumber mosaic virus and the citrus tristeza viral. Plant viruses are less easily spread than bacterial or animal viruses. Viruses can spread through contact between plants and are transmitted via fungi, nematodes, and insects.
Viruses can cause many diseases in humans and animals. Viruses can cause anything from a simple cold to potentially fatal illnesses such as meningitis. Although there are vaccines available for viral infections, some viruses can mutate and become resistant. We may need to get a new flu vaccine every year. Even if it’s not possible to cure the disease, many people are able to manage its symptoms.