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The Mystery of Retroviruses
A retrovirus is a virus
:A common alternate meaning of virus is computer virus. Other meanings, as well as a discussion of pluralization, are at virus (plural)
A virus is a small particle which can infect other biological organisms. Viruses are obligate intracellular parasites meaning that they can only reproduce by invading and taking over other cells as they lack the cellular machinery for self reproduction. more...
A Retrovirus is a virus which has a genome In biology, the genome of an organism is a complete DNA sequence of one set of chromosomes; for example, one of the two sets that a diploid individual carries in every somatic cell. When people say that the genome of a sexually reproducing species has been "sequenced," typically they are referring to a determination of the sequences of one set of autosomes and one of each type of sex chromosome, which together represent both of the possible sexes. Even in species that exist in only one sex, what is described as "a genome sequence" may be a composite from the chromosomes of various individuals. In general use, the phrase
Ribonucleic acid (RNA) is a nucleic acid, consisting of a string of nucleotides. It is biochemically distinguished from DNA by the presence of an additional hydroxyl group, attached to each pentose ring; as well as by the use of uracil, instead of thymine. RNA transmits genetic information from DNA (via transcription) into proteins (by translation).
Reverse transcriptase is an enzyme used by all retroviruses that transcribes the genetic information from the virus from RNA into DNA, which can integrate into the host genome. Usually, transcription only runs from DNA to RNA, catalyzed by RNA polymerase. An example of this kind of enzyme is the reverse transcriptase from the human immunodeficiency virus type 1 (PDB 1HMV , EC 2.7.7.49).
Ribonucleic acid (RNA) is a nucleic acid, consisting of a string of nucleotides. It is biochemically distinguished from DNA by the presence of an additional hydroxyl group, attached to each pentose ring; as well as by the use of uracil, instead of thymine. RNA transmits genetic information from DNA (via transcription) into proteins (by translation).
DNA dna (lower case) refers the enzymes involved in dna replication.
Types
* dnaA
* dnaB
* dnaC
* dnaG
DNA (uppercase) refers to deoxyribonucleic acid. See DNA.
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for insertion by integrase HIV integrase is an 32 kDa protein produced from the C-terminal portion of the Pol gene product. The integrase protein contains three domains: an N-terminal HH-CC zinc finger domain believed to be partially responsible for multimerization, a central catalytic domain and an C-terminal DNA binding domain. Integrase is responsible for the integration of proviral DNA into the host genome, which is essential for HIV replication. Integrase, therefore, remains a promising potential target for new anti-HIV therapeutics.
The virus itself is just a storage form for its RNA; the reverse transcription takes place in the host's cytosol The cytosol (as opposed to cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. Proteins within the cytosol play an important role in signal transduction pathways, glycolysis, and act as intracellular receptors and ribosomes. In prokaryotes, all chemical reactions take place in the cytosol. In eukaryotes, the cytosol contains the cell organelles. In plants, the amount of cytosol can be reduced due to the large tonoplast (central vacuole) that takes up most of the room of the cell interior.
A retrovirus' genome integrated into the host's genome is called a provirus A provirus is a retrovirus that has integrated itself into the DNA of a host cell. To do this, the RNA of the retrovirus was transcribed into DNA by reverse transcriptase, then inserted into the host genome by an integrase.
A provirus is not active while integrated into a host genome in this way. Instead, it is passively replicated along with the host genome and passed on to the original cell's offspring; all descendants of the infected cell will also bear proviruses in their genomes. Eventually, in response to changes in the host's environmental conditions or health, the provirus will excise itself from the genome again and resume activity as a virus. This results in the destruction of its host as its protein synthesis machinery is hijacked to produce more viruses. source...
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Retroviruses are viruses whose genome consists of RNA not DNA. HIV-1 and HIV-2, the agents that cause AIDS, are retroviruses. source...
see also:
Gelderblom Definitions
Pasteur Institute Definitions - Rules of Isolation
Robert Koch Postulates
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