(d)+Pathogen+overview

(7) What is a pathogen? A pathogen is an organism or virus that causes a disease in any other organism. (8) Draw up a table to show one example of a pathogen from each of the following group (virus, bacteria, fungi, protozoa, flat worms & round-worms).

The adenovirus consists of a slender shaft with a globular head. Adenoviruses can infect humans, and can cause respiratory illness or conjunctivitis ('pink eye'). **Herpes Virus** Herpes viruses are found in a wide range of hosts; at least seven different species are known to infect humans, including herpes simplex. Genital herpes has no cure. **Influenza** The influenza virus causes acute upper respiratory disease in humans, usually accompanied by a fever. These viruses are roughly spherical, and about 200 millionths of a millimetre in diameter. || This pathogenic bacteria causes food poisoning by producing a toxin that damages the nerves. This leads to progressive muscular weakness and even paralysis. If the toxin affects the respiratory muscles, it could lead to respiratory failure, leading to death. **Chlamydia** Can cause pneumonia, urinary tract infections and coronary heart disease to some extent || Infections on the bloodstream and major organs **Histoplasmosis** Infection on the lungs **Cryptococcosis** Occurs in the tissues covering brain and spinal cord resulting in meningitis || Cause severe ulcerations of the large intestine. || **Tapeworms** Live in humans after consuming unprepared meat. **Flukes** Live on the skin, mouth, gills Become weak and often die as a direct result of the fluke infection or because they cannot recover from other diseases in a weakened condition. || **Hookworm** Use hooks to burrow into skin and enter the bloodstream. Travel through the blood to the lungs. Causes weakness and poor growth, **Trichinella** Causes a disease known as Trichinosis. Travel through the bloodstream and live in the intestines of the host. Burrows into organs and tissues which causes extreme pain for the host. ||
 * **Pathogens** || **Examples** ||
 * **Virus** || [[image:adenovirus.PNG width="159" height="81"]] **Adenovirus**
 * **Bacteria** || **Clostridium botulinum**
 * **Fungi** || **Candida**
 * **Protozoa** || **Balantidum coli**
 * **Flat worms** || [[image:tapeworms.PNG width="105" height="160"]]
 * **Round worms** || [[image:hookworm.PNG width="140" height="140"]]

(9) List the 6 key methods by which pathogens… (a) Are transmitted
 * Droplet infection
 * Pathogens enter the body through the nose
 * Occurs after pathogens are coughed or sneezed out by someone else
 * By body fluids
 * Pathogens enter body through breaks in the skin
 * Examples: Hepatitis, AIDS


 * Contaminated Food
 * Pathogens enter the body through the mouth


 * Contaminated water
 * Pathogens enter the body through the mouth


 * Direct contact
 * Includes sexual contact


 * Vectors
 * Pathogens enter through skin or mouth

(b) Gain entry into the body Pathogens enter the body, as we breath them in, take them up by eating/drinking contaminated food or possibly exchange body fluids with another person. However, they might also move through small cracks in our skin. (The list of transmission of pathogens basically shows how they enter our body)

(10) Antibiotics (a) Where do antibiotics originate?

In the ancient times, the Greeks, the Babylonians and the Serbians and the Russians treated infections with mould or warm soil. Although it was unclear HOW the antibiotics worked, they always cured the infection. In the 17th century, British scientists accidentally discovered the antibiotic penicillin. (b) How do they work?

Antibiotics only work on eukaryotes:


 * Destroys cell walls - only present in eukaryotes, so can only work on them
 * Disrupts metabolic pathways such as protein synthesis
 * Also disrupts DNA replication to prevent eukaryotes from reproducing

(c) Why are the “human patient” cells not affected?
 * Do __not__ work on viruses or prokaryotic cells
 * Obvious: Anti - biotic not anti-viral

Bacterial cell walls have a substance called peptidoglycan

(d) Explain why virus cells are not affected, and bacteria cells are.
 * Antibiotics attack that
 * Human cells do not have this component, not affected by antibiotics

Antibiotics stop metabolic pathways such as protein synthesis


 * Viruses do not carry out metabolic pathways themselves but rely on (human) host cells to do it for them
 * Human host cells are not affected, so pathways of viruses are not affected


 * Viruses do not have a cell wall and are therefore not killed by antibiotics