The viruses has the properties that distinguish it from other microorganisms, namely:
1. The virus is contained in the body of one of the nucleic acid, DNA or RNA only;
2. In the process of reproduction, only necessary nucleic acid;
3. The very small size of about 20-300 milimikron;
4. The virus does not have the ability to multiply outside of living cells, it can be said that the virus is not a living being self-sufficient, but a living creature that utilizes living cells to reproduce themselves;
5. Multiplication occurs in the cells of the host;
6. Can be crystallized (as inanimate) and can be melted again.
Shapes of virus
The virus can be oval, rod (lengthwise), the letter T, and can also be spherical. The virus has a very simple structure. Viruses consist only of genetic material such as DNA or RNA surrounded by a protective protein called a capsid. The capsid is built by the subunits are identical to each other, called capsomeres. Capsomeres form is very symmetrical and someday may crystallize. In some viruses, such as herpes viruses and influenza viruses, can also be equipped by a cover or envelope of lipoprotein (lipid and protein).
Packaging is a plasma membrane derived from the host cell the virus. A virus with genetic material encased by wrapping a protein called viral particles or virions. The virus is not a cell or living beings because they do not have the cytoplasm and cell organelles do not perform as well as the metabolism is very small so it is not possible to have a cell structure.
Virus structure
The form of the virus (bacteriophage) consists of a head, casing, and a tail. Hexagonal-shaped head, comprised of capsomeres that surround DNA. One unit that makes up the capsid protein called capsomeres. Tail sheath serves as penginfeksi. Fibers contained in the base of the tail sheath tail serves as the recipient of stimuli. In addition to the influenza virus, the viral core consists of only one nucleic acid sequence. A nucleic acid sequence containing 3,500 to 600,000 nucleotides. Deoxyribonucleid Acid (DNA) and Ribonucleid Acid (RNA) is a substance that carries the genetic code of the virus heredity. Based on its core constituent, the virus can be divided into viral DNA and RNA viruses. Examples of DNA viruses are the smallpox virus. Examples of RNA virus is influenza virus and HIV.
Virus size
Viruses are very small and can only be seen using an electron microscope. The size of the virus around 20-300 milimikron, much smaller than the size of bacteria, which is 10 microns. To prove that the virus is very small size, Iwanovski and M. Beijerinck experiment with filtering. It turns out the virus still qualify from the ceramic filter, bacteria serangkan filtered because it was bigger than the virus.
Living Viruses
Viruses cannot stand alone or live freely in nature. Viruses are parasites living in bacteria, plants, animals, and humans.
1. Virus Bacteria
No one any bacteria that do not contain viruses. Viruses that infect bacteria are bacteriophages. Bacteriophages can develop quickly so that in a short time can destroy a number of bacteria. Bacteriophages have a core of nucleic acids in the form of double-twisting DNA or RNA single spiral or single chain. Examples of bacteriophage is E. coli.
2. Plants Virus
Most diseases in plants caused by viruses. This virus attacks can result in economic losses are enormous, for example, a virus that attacks potato plants and tobacco. Genetic material from plant viruses are RNA. The virus can enter the interior of the cell actively or can be through injury, for example, injuries from rubbing on the leaves. In nature, the virus is transmitted by direct contact or through vectors. A large number of viruses can also be transmitted by insects. Viruses often multiply in the digestive tract of insects (persistent virus). Viruses can infect other plants after an incubation period in the insect. Meanwhile, persistent virus can be transmitted through insect bites directly.
3. Virus on Animal Pathogens
The animal viral genetic material is DNA or RNA double twisting single polynucleotide. The virus can cause rabies (hydrophobia), plague in chickens, Ebola in apes, and nail disease in cattle. The virus can be transmitted by direct contact or through intermediaries insects. For his research, the necessary animal experiments or eggs that have been incubated. In addition, the virus can also be propagated by tissue culture. This multiplication can be done in a laboratory.
4. Attacking virus that Human
Viruses that infect humans, among other things, the chickenpox virus, smallpox, measles, influenza, polio, eye belek, hepatitis, dengue, diarrhea, HIV AIDS, and the AI virus. The virus can be transmitted to humans by direct contact or indirectly. Belek eye, influenza, and smallpox can be transmitted by direct contact or through the air. Hepatitis and polio can be transmitted through contaminated well water and a spoon or plate of former patients or patients with sweat. Dengue fever can be transmitted through the bite of Aedes aegypti. Meanwhile, the HIV AIDS virus can be transmitted through needles, saliva, blood transfusions, milk, placenta to the fetus of pregnant women, sexual intercourse, and vaginal fluid and semen.