biology- module 7

pathogen

a disease causing agent

disease

any condition that disrupts the normal functioning of an organism. It usually cause symptoms, ranging from mild to severe

infectious disease

A disease that can be spread from one organisms to another and is caused by pathogens

non-infectious disease

A disease that is not caused by pathogens. It is caused by genetics, the environment and/or malfunctions within cells

virus structure

non celluar, 30-300nm, cannot reproduce on their own (needs a host)

bacteria structure

single celled prokaryotic organisms, have a cell wall, size range from 0.5-100 um

prions structure

non-cellular, 10nm, a protein, do not contain any genetic material

protozoans structure

single celled organism, have a cell membrane and membrane-bound organelles, reproduce by asexual binary fission, size range from 1-300 um

fungi structure

eukaryotic organisms, have a cell wall, do not produce their own food, can be multicellular or unicellular

macroparasites

larger multicellular organisms.

parasites

An organism that feeds off another living organism

endoparasites

lives inside host body

ectoparasites

live outside host body

microscopic

very small and cannot be seen with a naked eye

macroscopic

large enough to be seen without a naked eye or any devices that makes things look larger

bacteria

single celled prokaryotic organisms. They reproduce rapidly by binary fission. Some release toxins that damage tissues. eg. tetanus (human and animal), meningococcal disease (human only), crown gall (plant only)

virus

Non-living particles made of genetic material (DNA or RNA) surrounded by a protein coat called capsid. They invade host cells and use them to reproduce, destroying the cells. eg. HIV, smallpox

Fungi

Eukaryotic organisms that may be unicellular (yeast) or multicellular (mould). They feed by absorbing nutrients from living or dead matter. Eg. Athlete’s foot, ringworm, thrush

Protozoa

Single-celled eukaryotes that often live in water as parasites in hosts. They move using flagella or cilia. Eg. Malaria

Prions

Abnormal infectious proteins that cause other proteins in the brain to fold incorrectly, leading to brain damage. They do not contain DNA or RNA. Eg. Jakob disease

Disease transmission

refers to how pathogens spread from one host to another

Direct transmission

when pathogens are transferred directly from one person (or host) to another

Types of direct transmission

direct contact, droplet transmission, vertical transmission

Indirect transmission

 when pathogens are transferred via an intermediate object or organism

Types of indirect transmission

 Airborne transmission (air), Fomite transmission (contaminated objects), Vector transmission (by another organism), water borne transmission, food borne transmission

Epidemic

rapid spread of disease to a large number of people in a specific population or region in a short amount of time

Endemic

when a disease is constantly present in a population or region

Pandemic

global epidemic spreading across multiple countries or continents

Non-cellular pathogens

disease-causing agents that are not made of cells and cannot reproduce on their own

cellular pathogens

disease-causing microorganisms made of living cells that can reproduce independently

microorganisms

tiny living organisms that are too small to be seen without a microscope,

macroorganisms

living things that are large enough to be seen with the naked eye

Robert Koch

He was mainly known for proving that specific microorganisms cause specific diseases

Robert Koch discoveries

 His role in the development of germ theory, his postulates, his techniques for creating pure cultures, used to treat tuberculosis, cholera and anthrax

Robert Koch postulates

1. The microorganism must be present in all cases of the disease but absent in healthy individuals.

2. It must be isolated and grown in pure culture.

3. The cultured microorganism should cause the disease when introduced into a healthy host.

4. The same microorganism must be re-isolated from the experimentally infected host

Louis Pasteur

He was mainly known for proving that microorganisms cause disease and developed methods to prevent infection

Louis Pasteur discoveries

1. Disapproving the spontaneous generation: In the 1860s, Pasteur used his swan-neck flask experiment to show that microorganisms come from other microorganisms, not from non-living matter.

2.  Germ theory of disease: Proposed that specific diseases are caused by specific microbes.

3. Pasteurisation: Developed a process of heating liquids (like milk and wine) to kill harmful bacteria without changing the taste.

4. Vaccines for rabies