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.

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

A virus is a small capsule that contains DNA or RNA, viruses, unlike bacteria are not self sufficient and need a host in

For example, viruses do not use energy and raw materials to grow and reproduce, and they are not made of one or more of the basic fundamental units of life – a cell. Compared to a cell, which includes organelles that enable the structure to grow and reproduce, a virus can only reproduce if another cell is present and that cell has organelles that the virus can inject its own DNA or RNA into and use it for its own replicating or mutating purposes. Viruses are made of a protein coat or capsid with its DNA or RNA genetic material enclosed inside of the capsid. In comparison, in addition to having organelles that use energy to help the cell develop, grow, and reproduce with the help of DNA, the cell by definition is enclosed in a membranous boundary,

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.

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.

The process of evolution results when organisms reproduce more individuals than the environment can support, genetic variation naturally and inevitably occurs, the organisms that are the most successful within their habitat survive, and those that are deficient and weak are eliminated. The survivors of this ecological pressure are able to flourish, reproduce, and pass their favorable genes onto subsequent generations. Many biologists believe that viruses evolved after the appearance of the first cells and favor the hypothesis that they "originated from fragments of cellular nucleic acids, [DNA or RNA], that could move from one cell to another" within an organism (Campbell, Mitchell, and Reece 330). This theory asserts that a portion of DNA or RNA initially became separated from the remainder of the cell's genome, and the newly formed virus then migrated into another cell. Isolated fragments of DNA or RNA would be biologically inert; therefore, viruses have been "engineered by the forces of evolution" to maximize their survival as mobile, parasitic organisms (Preston 159). Viruses, as mere segments of nucleic acids, have developed various adaptations that ensure their reproduction, their transport from cell to cell, and their survival at the expense of another organism.

A virus depends on the host’s energy to stay alive and needs the host to be part of a living organism. The word virus comes from the Latin words of poison or toxic. Sense viruses don’t leave any fossil remains it’s hard to trace them over time.

Viruses, after entering a host cell, integrates its genome with the host cell’s DNA using the enzyme reverse transcriptase. During normal DNA replication, the virus’ genome will be replicated to produce more viral particles. During this process, host cell genes can be triggered by viral genes

It is known that viruses were made up of DNA inside a protein. Viruses multiply by inhabiting the host cell and taking over its functions.

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.

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

Viruses are microscopic organisms that lack the enzymes needed to manufacture cellular components. Once infected, the virus can insert its genetic material and force the host the make copies. To combat these viruses scientists are using antiviral drugs that can stop the virus from infecting the host.

The article first addresses the issue of whether or not to consider viruses as living. Although viruses used to be thought of as being biological chemicals due to the fact that they consist of nucleic acids

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