Understanding Viruses: Characteristics, Transmission, and Prevention

This assignment discusses the topic of viruses. It highlights their characteristics, such as being non-cellular microbes that are small in size and composed of nucleic acids, proteins, and lipids. The structure of a virus is also explained, which includes capsid head, collar, sheath, baseplate, spikes, tail fibre, and reproduction occurs by using host cells. Additionally, the assignment focuses on HIV/AIDS, discussing its modes of transmission, symptoms, life cycle, treatment, and prevention measures, such as using sterilized needles, condoms, avoiding multiple sexual partners, and checking blood before transfusion.

BACTERIA
A. Characteristics
 Bacteria is defined as a unicellular microorganisms (Brown and et.al., 2015).
 Prokaryotic organisms without defined cell organelles.
 Occur in single form or in colonies.
 These do not have natural death.
 Classified into three types based on shape:
1. Bacilli - Rod shaped bacteria known as
2. Cocci - Spherical shaped
3. Spirilli - Curved shaped
Cell structures
Illustration 1: Cell structure of Bacteria
(Source : Hoover and Steenson, 2014).

The cell structure of bacteria comprises of:
Cell wall:
 It is made up of glycoprotein murein (Saier, 2014).
 It provide support and rigidity to bacterial cell.
 It protects cell in hypotonic medium.
Plasma Membrane:
 It is also called cytoplasmic membrane.
 It is mainly composed of proteins, phospholipids and carbohydrates.
 It helps in transportation of substances in the cell (Gouin, Torres and Cossart, 2015).
 Provides mechanical barrier to cell.
 Act as semi-permeable membrane which permits entry of selected substances into the cell.
Cytoplasm:
 It helps in cellular growth as well as replication.
 Maintains metabolism in bacterial cell ().
Ribosomes:
 tiny granular structure made up of RNA and proteins.
 Site of protein synthesis.
Plasmid: these are tiny circular DNA
Capsule:
 It covers outer part of cell wall.
 It protects cell from dryness.
Pili: These are protein structures that fixes bacteria to surfaces
Flagella:
 It is tail like structures
 helps in movement of bacterial cell.
Reproduction :

 Bacteria reproduces and grows by binary fission.
 In this process cell divides into two half to form daughter cells.
 The cytoplasm divides and two identical cells are formed.
Environment:
Bacteria are abundantly found in water bodies, deserts, hot springs and bodies of other organisms.
Disease causing bacteria in humans
Diseases in humans Causal Bacteria
Tuberculosis : infection of lungs Mycobacterium tuberculosis
Syphilis: sexually transmitted disease Treponema pilludum
Cholera: caused by intake of contaminated food Vibrio cholerae
Pneumonia : inflammatory lung disease Streptococcus pneumoniae
B. Transmission methods
Bacterial transmission involves following methods:
Entry of microbes in hosts :
 Bacteria enter into human body through contaminated food and water (Saier, 2014).
 Consumption of contaminated water from uncontrolled water resources.
Illustration 2: Binnary fission in bacteria
(Source:Gouin, Torres and Cossart, 2015)

 Causes outbreak of cholera by multiplying in host body.
Transport to new host:
 In this method, bacteria are transported to new host through human touch.
 For example: Syphilis is caused during sexual contact in humans.
 Coming in contact with infected objects used by diseased host.
C. Factors for pathogenic infection in hosts
Low defence mechanism in hosts (Tunkel, 2012.)
 Weak immunity of host gives favourable condition for invasion of cholera bacteria.
 Defect in phagocytic system cases bacterial infection
Toxins: Toxins produced by bacteria are proteins that causes cholera in hosts (Hoover and Steenson,
2014).
Symptoms of Cholera:
 Diarrhoea
 Vomiting
 Muscle cramps (Brown and et.al., 2015).
 low blood pressure
 Increased heart rate
Treatment and Prevention
 Drinking safe water from clean water sources (Gouin, Torres and Cossart, 2015).
 Washing fruits and vegetables before eating.
 Washing hands properly before meals.
 Intake of oral rehydration salts to fulfil salt deficiency
 Intake of fluids to keep the body hydrated.
VIRUS
Characteristics
 Viruses are non cellular microbes (Cullen, 2015).
 They are considered both living and non living organisms.
 They are measured in nanometres as they are very small.
 They are composed of nucleic acids, proteins and lipids.
 Viral genetic material is composed of DNA and RNA.
Cell Structure

Viruses have have complex structure.It is comprised of:
 Capsid head: It is outer protective protein coat.
 Collar
 Sheath
 Baseplate
 Spikes
 Tail fibre
Reproduction
 Viruses cannot reproduce by their own.
 They need host host body to grow and reproduce.
Environment:
 Virions remain dormant outside living cells
 But act as living organisms in host body.
Disease causing viruses in humans
Diseases in human Causal viruses
AIDS : Acquired Immuno Defficiency Syndrom HIV human Influenza virus
Illustration 3: Cell structure of Virus
(Source :Cullen, 2015)

Influenza infect upper respiratory tract Orthomixovirus
Chicken Pox affect skin Varicella virus
Modes of Transmission of HIV virus
Virus infect the host body by following means:
 unprotected sexual contact
 transfusion of infected blood (Maartens, Celum and Lewin, 2014).
 breastfeeding
 Injecting non sterilized needles
Symptoms of AIDS
 Diarrhea
 Fatigue (Pearlstein and et.al., 2014).
 Fever
 Weight loss
 Low concentration levels
 Loss of appetite
Life Cycle of HIV
Illustration 4: Life Cycle of HIV virus
(Source: Salamon, 2013).

Treatment and Prevention
There is no vaccine to cure HIV (Dovel and et.al., 2015).
It can only be prevented by following means:Gouin, E., Torres, J. J. Q. and Cossart, P., 2015
 Use of sterilized needles in injections.
 Use of precautions like condoms while sexual contacts.
 Avoid sexual contact with multiple partners.
 Avoiding direct contact with infected blood on injured skin surfaces.
 Checking the blood before transfusion (Snyder, Bolduc and Young, 2015).

REFERENCES
Books and Journal
Brown, C. T. and et.al., 2015. Unusual biology across a group comprising more than 15% of domain
Bacteria. Nature. 523(7559). pp. 208-211.
Cullen, B. R., 2015. The virology–RNA biology connection. RNA. 21(4). pp.592-594.
Dovel, K. and et.al., 2015. Men's heightened risk of AIDS-related death: the legacy of gendered
HIV testing and treatment strategies. AIDS. 29(10). pp.1123-1125.
Gouin, E., Torres, J. J. Q. and Cossart, P., 2015. Intracellular Bacteria Find the Right Motion. Cell.
161(2). pp. 199-200.
Hoover, D. G. and Steenson, L. R., 2014. Bacteriocins of lactic acid bacteria. Academic Press.
Maartens, G., Celum, C. and Lewin, S. R., 2014. HIV infection: epidemiology, pathogenesis,
treatment, and prevention. The Lancet. 384(9939). pp.258-271.
Pearlstein, S. L. and et.al., 2014. Youth in transition: life skills among perinatally HIV-infected and
HIV-exposed adolescents. Journal of pediatric psychology. 39(3). pp.294-305.
Saier, M. H., 2014. Mechanisms and regulation of carbohydrate transport in bacteria. Academic
Press.
Snyder, J. C., Bolduc, B. and Young, M. J., 2015. 40 Years of archaeal virology: Expanding viral
diversity.Virology. 479. pp.369-378.
Online
Salamon, M., 2013. AIDS & HIV: Treatment & Prevention. [Online] Available through
<http://www.livescience.com/34699-hiv-aids-symptoms-treament-prevention.html>. [Accessed
on 5th December 2015].
Tunkel, A. R., 2012. Factors Facilitating Microbial Invasion.[Online] Available through
<http://www.msdmanuals.com/professional/infectious-diseases/biology-of-infectious-disease/
factors-facilitating-microbial-invasion>. [Accessde on 5th December 2015].