Welcome to Advanced Biology blog!
My name is Anel Turgambayeva. I am a first year undergraduate student
with Biology major and a host of this page. I have taken a class in
Modern Biology I. Since I have been really interested in the area of
Microbiology, I decided to create a blog that is aimed to introduce you with
the fascinating world of microbes and give the detailed information about these
microscopic creatures.
What Virology is about?
According to the College dictionary, virology– is a biological science that concerned with the study of the smallest
microorganisms – viruses. This
discipline is focused on the exploration of the nature,
structure, chemical composition, relationship with the organism and the
environment, ecology, prevention and treatment of viral diseases.
Are viruses alive?
Viruses are the most mysterious creatures among microorganisms. Viruses differ significantly from other types of microorganisms. They are
acellular life forms and incapable of self-reproduction and metabolism. For
this reason viruses follow the parasitic way of life:
they use the internal machinery of the host cell to replicate, grow and produce
their own proteins. As viruses do not perform the functions of the living
things, they are considered to be non-living structures.
Structure of viruses
As
it was mentioned before, viruses do not have a cellular structure. Each virus
is arranged in a very simple way - it consists of genetic information carrier
that located in the centre of virus, and the shell.
Genetic
material is a short nucleic acid molecule which forms the core of the virus.
The nucleic acid of viruses can be represented as DNA or RNA. Shell that
encodes that genetic core of virus called capsid. It consists of subunits - capsomeres,
each of which constituted from one or two protein molecules. The structure of
the virus is illustrated in figure1.
figure 1. Structure of virus
Shapes and symmetry of viruses
The capsomers of each virus arranged in a certain type of symmetry. If capsid acquires tubular as tobacco mosaic virus form this type of symmetry is called helical (figure 2, at the right). In isometric symmetry viral capsid have more spherical shape (figure2, in the middle). In the case of complex symmetry capsid has a cubic shape and located within the nucleic acid that stacked spirally (figure 3). Correct geometry of the capsid even allows viral particles together to form a crystalline structure.
figure 2. Viral symmetry. Helical (right) and Isometric (middle)
figure 3. Complex viruses
Viruses are diverse in sizes.
They are roughly 17nm – 1000nm in diameter, which is approximately 50-fold less
size of bacteria. They cannot be seen under the light
microscope, as their length is less than the wavelength of light. Thus to observe the structure of viruses the electronic microscope is
applicable.
Viral diseases
Despite of the simplicity of the structure, viruses are capable to cause
different diseases virtually in all organisms, including bacteria, plants and
animals. There is a great number of viral diseases among people, The most
common of them are influenza, smallpox, polio and etc. and I
would like to describe in details
one of the most dangerous
human viral diseases known as AIDS.
AIDS
AIDS
- one of the most important and tragic problems encountered by the world at the
end of the 20th century. The agents that cause AIDS are known as Human
Immunodeficiency Virus (HIV). HIV is known as a killer virus. The uniqueness of
these pathogens is in the way they enter and infect a cell: the coat of HIV
fuses with the plasma membrane of a host cell and virus releases its genetic
material (RNA) and other chemicals into the cell. Further, HIV starts to
reproduce and manufacture necessary for growth and development things in the
host cell. The target cells of that agents are "helper"
T-4 lymphocytes, cells that destroy infectious agents and disease. As the
number of T-4 lymphocytes falls the effectiveness of the immune system is
lowered significantly. Thus, even the minor infections can lead to
serious consequences in patients with AIDS.
The treatment of
AIDS does not exist yet, but there are a lot of drugs that slow down the destruction
of the immune system and are thus able to significantly prolong the lives of
HIV-infected patients.
Reference list
"BIO-DIVERSITY - PART I." Boddunan.
https://www.boddunan.com/articles/science-nature/71-wild-life/8521-bio-diversity-part-i.html (accessed September 26, 2014).
Raven, Peter H.,
and George B.Johnson. 2001. “Viruses”. Biology.
http://www.mhhe.com/biosci/genbio/raven6b/graphics/raven06b/other/raven06_33.pdf
(accessed September 25, 2014).
"Virology dictionary definition". Browse Webster's New
World College Dictionar. 1996. http://www.yourdictionary.com/virology
(accessed September 25, 2014).
"Capsomer definition." Mondofacto. 2009.
http://www.mondofacto.com/facts/dictionary?query=capsomer(accessed September 26, 2014).
"T4 helper lymphocyte". Mondofacto. 2009.
Mahy J. and Pattison R. 1984. Structure of viruses.Pages: 33-36.
Published by Cambridge University Press. http://crystal.harvard.edu/lib-sch/HarrisonS-84-Microbe-_-29.pdf. (accessed September 25, 2014).
What Is HIV? http://www.aids.gov/hiv-aids-basics/hiv-aids-101/what-is-hiv-aids/ (accessed September 26, 2014).
