Define the terms disease - condition that negatively affects the structure or function of an organism. pathogens - a microorganism/microscopic (such as bacteria or virus) that can cause disease.
Give examples of pathogens and their unique features.
Pathogens are microscopic organisms that cause or have the potential to cause disease. Diseases caused by pathogens are called infectious diseases. This means the disease can be transferred from an infected organism to another organism. Different types of pathogens include bacteria, viruses, protists (amoeba, plasmodium, etc.), fungi, parasitic worms (flatworms and roundworms), and prions.
Flatworm -
Parasitic worms that are spread through contact with contaminated food and water.
In humans, most of these worms infect the intestines and sometimes spread to other areas of the body. Intestinal parasites attach to the walls of the digestive tract and feed off of the host. They produce thousands of eggs that hatch either inside or outside (expelled in feces) of the body.
Yeasts, moulds and mushrooms are examples of fungi.
Disease caused by fungi is rare in humans.
Protozoan -
Protozoa are tiny unicellular organisms.
They cause disease by parasitically feeding off the host and multiplying at the expense of their host.
Parasitic protozoa are commonly transmitted to humans through contaminated soil, food, or water. They can also be transmitted by pets and animals, as well as by insect vectors.
Bacteria -
Bacteria are living cells and can multiply rapidly. Once inside the body they release poisons or toxins that make us feel ill.
Virus -
Viruses are unique pathogens because they are segments of DNA or encased by protein envelope (like a m&m - the inner chocolate is the DNA segment and the outer coloured shell is the protein envelope).
Viruses can only reproduce inside host cells, and they damage the cell when they do this. A virus can get inside a cell, take over and make hundreds of thousands of copies of itself. Eventually the virus copies fill the whole host cell and burst it open. The viruses are then passed out of the body in the bloodstream, the airways, or by other routes.
Prion -
A prion is a unique type of pathogen that is not an organism at all but a protein.
Prion proteins have the same amino acid sequences as normal proteins but are folded into an abnormal shape.
This altered shape makes them infectious as they influence other normal proteins to take on an infectious form.
Prions typically affect the central nervous system. They can cause brain deterioration.
Explain the germ theory - Germ theory of disease is based on the concept that many diseases are caused by infections with microorganisms. Such microorganisms can consist of bacterial, viral, fungal, or protist species.
Distinguish and give examples of infectious and non-infectious diseases
diseases can be infectious or noninfectious.
Infectious diseases are illnesses that are contagious, meaning they can be spread from one person to another. Infectious diseases are caused by microorganisms, called pathogens, or what we commonly refer to as germs. Some types of infectious diseases include viruses, bacteria, fungi and one celled animals called protozoa. The thing to remember is that infectious diseases can be passed from one person to the next. A good example is which is spread through sexual relations.
Noninfectious diseases are not caused by disease causing organisms or pathogens. These diseases are caused instead from genetic, lifestyle or the environment. Some good examples of these diseases include Cancer, Cardiovascular Disease and Diabetes. Noninfectious diseases can progress slowly but lead to rapid death. Examples of these kinds of diseases are stroke, cancer and heart attack.