Write An Essay On Hepatitis B Virus

The virus fuses with the cell’s plasma membrane. The capsid proteins are removed, releasing the viral proteins and RNA. Reverse transcriptase catalyzes the synthesis of a DNA strand complementary to the viral RNA. Reverse transcriptase catalyzes the synthesis of a second DNA strand complementary to the first. The double-stranded DNA is incorporated as a provirus into the cell’s DNA. Proviral genes are transcribed into RNA molecules, which serve as genomes for the next viral generation and as mRNAs for translation into viral proteins. The viral proteins include capsid proteins and reverse transcriptase (made in the cytosol) and envelope glycoproteins (made in the ER). Vesicles transport the glycoproteins from the ER to the cell’s plasma membrane. Capsids are assembled around viral genomes and reverse transcriptase molecules. New viruses bud off from the host cell.

The biological significance of this article is due in part to the fact that viruses are being considered as partway-living things. Even though they are only halfway living, per se, they are still an important part of the study of living things because of the unique way in which they “live” and continue to reproduce by taking advantage of host cells. The information in this article relates to biologists in that viruses provide an entirely different element of potential life, as they are a cause for reconsideration when it comes to defining and determining life and non-life forms. This

Unlike bacteria, that have everything it needs to reproduce, viruses need to use a living cell's organelles in order to replicate.

do not have their own energy, but rely upon the energy available within the living cell which the virus has infected.” (MadSci). Without a host cell, viruses do not have any energy to do their thing.

Viruses are microscopic particles that invade and take over both eukaryotic and prokaryotic cells. They consist of two structures, which are the nucleic acid and capsid. The nucleic acid contains all genetic material in the form of DNA or RNA, and is enclosed in the capsid, which is the protein coating that helps the virus attach to and penetrate the host cell. In some cases, certain viruses have a membrane surrounding the capsid, called an envelope. This structure allows viruses to become more stealthy and protected. There are two cycles in which a virus can go into: lytic and lysogenic. The lytic cycle consists of the virus attaching to a cell, injecting its DNA, and creating more viruses, which proceed to destroy the host. On the other hand, the lysogenic cycle includes the virus attaching to the cell, injecting its DNA, which combines with the cell’s DNA in order for it to become provirus. Then, the provirus DNA may eventually switch to the lytic cycle and destroy the host.

Because they do not have a cell membrane to receive material selectively, and also there is no way to make food or produce energy on its own. A virus is closed in on itself. If cannot respond to any stimuli outside of being linked with a host cell.

material of some viruses. RNA molecules are like DNA. They have a long chain of

Viruses - are extremely small particles made from protein and either DNA or RNA. They are not made up of cells instead they invade the living cells of other organisms and use them to produce many copies of

The virus starts by getting a host cell and either uses it right away then kills it or kills right away usually they use it first. When the virus invades a body, It collides with the cell that spicks and propherances then they brush against each other and it if they fit together become one. The viruses is also able to hide from the immune system therefore avoiding being killed so it can reproduce. Then the virus gains control of a cell by injecting its genes into the cell and makes it do whatever it wants for the benefits of the virus not the cell. Of course while you have a cell doing the dirty work for you. The viruses make is own offspring/ copies of itself and takes of over and invading surrounding cells.

Viruses are parasites using its host 's cells to replicate its own genome (Freeman, 2011). Viruses have either a deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) genome that affects its specific named genome. Types of RNA viruses include positive strand, negative strand, double strand and RNA transcriptase. RNA viruses have evolved into effective pathogens that mutate at high rates. This allows them an advantage over their host to effectively evade the immune system through several mechanisms, such as mimicry, avoiding cell lysis, and phagocytosis. Their ability to bypass a cell 's normal process of proof-reading and error correction is what makes RNA viruses such effective pathogens. Almost all RNA viruses are termed emerging infectious diseases because they are already known, but are increasing rapidly in new areas. There are a few emerging infectious RNA viruses that have reappeared into the population and have the potential to cause an epidemic.

They exist around the world and cause diseases in different types of animals and human. Poxvirus infections usually cause the formation of lesions, skin nodules, or a rash. Examples of poxviruses are smallpox, chickenpox, and monkeypox infections. Poxviruses replicates in the cytoplasm unlike other DNA viruses. Intracellular virion (IMV) particles bind to unknown receptors and fuse the cell membrane. Extracellular enveloped virion (EEV) particles bind to unknown receptor(s) and are endocytosed into the cell. The viral core particle which contains the genome and other enzymes including viral DNA – dependant RNA polymerase are released into the cytoplasm. Early genes are transcribed and translated as soon and the core particle enters into the cytoplasm of the cell. The core particle moves to the outside of the nucleus. And the viral nucleoprotein complex which included the viral genome is released. At this step the viral genome is replicated as a concatemer and transcription and translation of intermediate genes takes place. The viral late genes are then transcribed and translated.” Concatemeric intermediates are resolved into linear double-stranded DNA and packaged with late viral proteins into immature virions (IV). IVs mature into IMVs via a un described mechanism which may include processing of the IV through the Golgi apparatus. The IMVs are transported to the periphery of the cell where they are released

The protective capsid helps the virus escape detection and destruction during the invasion of the host. When the virus reaches the target cell, biochemical reactions between the capsid and cell wall allow the virus to latch on and inject its genome into the cell’s interior. Once inside, the viral genetic material insinuates itself into the host’s DNA or RNA. In an efficient feat of natural bioengineering, the host cell’s genetic machinery now does the rest of the work for the virus. The cell, which had already been making copies of its own genome, now also replicates that of the virus. Coded within the viral material is the blueprint for making more copies of the viral genome. Further instructions command the production of capsids and directions for assembly of new viruses. After the host cell becomes engorged with viruses, it explodes, sending the new

A virus is a biological agent that reproduces inside cells of a living host. These microscopic, nonliving particles can infect all types of organisms ranging from plants to animals and even bacteria. Viruses consist of nucleic acid, RNA or DNA, which is surrounded by a protein coat. A virus is not alive until it inhabits a cell. It can inhabit a cell through soil, water, and the air through our noses, mouths and even breaks in skin. Once it does this, it can begin to replicate and grow accordingly. Viruses use their capsids, the protein coats, to enclose the DNA and then use their tails to attach to the cell and begin to inject their own DNAs. The best-understood and most abundant virus is called a bacteriophage. A bacteriophage is a virus

A virulent virus is more severe, the cell of the living host is completely taken over by the viral genome. Once inside the host cell, the viral genome replicates and kills the host cell upon exit. An example of this is HIV. HIV is a virus that presents immunodeficiency, the immune system being comprised results in a weakened ability to fight off infection. HIV is transmitted through blood and some bodily fluids (NHS 2014). The virion RNA integrates with the host DNA producing replications of the viral RNA, these replications form buds on the outer membrane of the host cell, these detach from the host cell and find new cells to infect, the host cell is eventually destroyed.

Viruses are especially adept at this. Helical viruses look rod shaped under a microscope and can be fixed or flexible (Gillen, 2007). Viruses lack the power to make up proteins and metabolize sugars and need a host to live. Viruses locally invade membranous tissue, replicates and grows and finally causes infection in the target organ (skin, lungs, or nervous system). The virus then opens to the bloodstream after injecting their DNA into a cell, bursting from the cell, destroying the cell and then continuing to infect other cells (Sompayrac, 2002). A central component of a viruses’ structure which allow it to operate as a pathogen is its antigens [See: Figure 1]. Viruses are refined in their power to adapt and mutate their antigens through antigenic variation which prevents the immune system from seeing the correct antibody, giving the virus time to spread (Craig and Scherf, 2003). HIV is a virus which prevents CD4+ cells (Th cells) from activating the body’s immune response, through cell signalling. Thus, when a virus enters the body, it can dominate the immune system in an HIV+ host; allowing for opportunistic infections, such as pneumonia, which can kill. Thus, the nature of viral infections is etiologic to a virus causing disease in hosts with a deficient immune system. In HIV, the virus remains latent in cells until viral transcription and translation