Mr. C\u2019s Top Ten Questions About Virus<\/p>\n
Question One: Are Virus living things?<\/p>\n
Non living Characteristics<\/p>\n
Living Characteristics<\/p>\n
they do not respire<\/p>\n
they do have DNA or RNA<\/p>\n
there is no cellular structure<\/p>\n
they do have proteins and enzymes<\/p>\n
they do not grow<\/p>\n
they have the potential to make other cells make copies of themselves, this is more like duplication than reproduction<\/p>\n
they can be crystallised due to harsh environments<\/p>\n
virus show diversity associated with the hosts they infect<\/p>\n
they cannot reproduce on their own<\/p>\n
* this is a great table for a test question\u2026.<\/p>\n
Question Two: What are virus and where did they come from?<\/p>\n
Virus may be linked to the original entity of life as a noncellular ancestor of cells
\nTheir means of existence may imply that they were once primitive organisms that loss cell structures in order to assist parasitic lifestyle.
\nThe genetic material within a virus is only a fragment of an original genome.
\nQuestion Three:<\/p>\n
What is the structure of a virus and how is it associated with its lifestyle.<\/p>\n
Most virus are composed of a protein coat which surrounds a small fragment of DNA or RNA.
\nMost virus are only visible with electron microscopes ranging in size from .015 to .45 microns.
\nSome of the protein coats are specialised for the host that the virus infects.
\nThe shape of the protein coat may vary from spherical shapes to bacteriophage which have additional structures to add attachment to host.
\nShapes are usually spherical, rod shaped or tadpole shaped.
\nQuestion Four: How are virus classified?<\/p>\n
Virus are classified by the host they infect
\nPlant virus: ( example tobacco mosaic virus)
\nAnimal ( by class: Aves : Bird, Insecta: insects) virus
\nBacteria virus or Bacterio phage
\nQuestion Five: How are virus transmitted?<\/p>\n
In plants: virus can be transmitted from contact with insects, direct contact between plant seeds, leaves or stems.
\nIn animals: virus can be transmitted from coughing, sneezing, talking, direct contact and insects.
\nQuestion Six: How do virus infect host<\/p>\n
A general infection follows the following pattern.<\/p>\n
The virus comes in contact with host cell and attaches to host cell.
\nViral Protein coat is either removed after absorption by host or virus injects nucleic material into host.
\nViral DNA or RNA is replicated by the host cell.
\nReplicated viral DNA or RNA is translated into proteins for viral enzymes and protein coat.
\nNew virus are assembled within host cell from replicated and translated material.
\nVirus either remain in host or host cell breaks due to too many virus within cell.
\nSpecialised infections:<\/p>\n
Bacteriophage: Virus that infect bacteria<\/p>\n
In this type of infection there is the possibility of two events<\/p>\n
a) A lytic cycle<\/p>\n
Virus attaches to host bacteria, an enzyme eats away the host’s cell wall and viral nucleic material is injected into host
\nViral nucleic material is incorporated into host nucleic material
\nViral nucleic material begins to replicate and translate its code, this takes over the bacteria normal cellular functions.
\nAs many as 100 or more copies of the original virus are made by host bacteria
\nThe host bacteria burst and virus is release to the environment. The word lytic comes from the Latin which means to burst open
\nb) A lysogenic cycle.<\/p>\n
Much like the lytic cycle the host bacteria is infected by the virus, however lyses of the bacteria does not happen immediately. Bursting of the cell only occurs when the bacteria become weakened or there is a change in the environment.<\/p>\n
c) Mutagenic<\/p>\n
some virus will not cause the cell to lyse or die but will cause mutations which can change the growth rate of the cell or the shape and size of cells. Some of these viruses have been linked to creating cancer cells. Remember\u2026one of the characteristics of cancer cells are their growth rate and change is morphology.<\/p>\n
Retrovirus Infections:<\/p>\n
A retrovirus is a RNA virus which infects the host in a unique fashion.
\nThe viral RNA serves as a template for the host cell to make a segment of DNA.
\nThis DNA is then encoded into the host’s genetic material.
\nThe cell does not die but changes due to the new encoded material.
\nThe mechanisms of this type of infection are still being researched.
\nQuestion Seven: Are all infections the same?<\/p>\n
The answer is no. There are at least three possible outcomes from an infection:<\/p>\n
Results of viral infection can be:<\/p>\n
A virulent infection:
\nThis is when the virus causes a lytic cycle and the host cell dies
\nA latent infection:
\nThis is when the virus either becomes part of host genome or remains dormant until changes in host cell and or external environment.
\nTumour producing infection:
\nThis is when the host cell is not destroyed but mutated causing the host cell to divide and produce cluster of cells that have changed from the original cell. If these cells remain dormant they are said to be benign and show themselves as a wart or tumour), if these cells become mobile, they are said to be malignant.
\nQuestion Eight: What diseases are caused by viral infections?<\/p>\n
Some common viral infections are:
\nviral pneumonia, the common cold, influenza, mumps, measles, German measles polio shingles chickenpox smallpox, AIDS virus hepatitis warts yellow fever cold sores hoof and mouth disease Ebstein Barr virus mosiacs in plants<\/p>\n
May be associated with some cancers, leukaemia\u2019s, and autoimmune disorders
\nSome lethal viruses: Ebola (95% fatality rate)
\nMost publicised virus: HIV<\/p>\n
Question Nine: Is there a way to treat or cure viral infections?<\/p>\n
One of the first methods of preventing infection by virus was done by the Chinese, who rubbed other individuals with skin scabs from those individuals who survived a viral infection such as small pox.
\nEdward Jenner, created a process called vaccination ( from the Latin origin vaca for cow : another famous cow story!) by exposing individuals to cowpox virus, which he noted prevented them from being infected from a more virulent virus for small pox.
\nIt is useless to treat a viral infection with antibiotics however people treated with a killed strain of virus or viral proteins may create their own antibodies to attack onto viral proteins.
\nQuestion Ten: How were virus discovered?<\/p>\n
Discovery of virus were initially related to nature of infection of hosts
\nActual viral material viral material was not purified until 1933 by Stanley. This particular material was crystallise tobacco mosaic.
\nIdentification of viruses has improved with the increased efficiency of electron microscopes.
\nBecause viral DNA\/RNA interacts with host nucleic material, viruses are continue to change and evolve.
\nIf you have any further questions you wish to explore\u2026contact Mr. C<\/p>\n","protected":false},"excerpt":{"rendered":"
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