SCIENCE- Disease Flashcards
what is an infectious disease?
an infectious disease is a disease caused by an organism or infectious agent. These are pathogens. Pathogens are organisms that cause diseases. Infectious diseases can be passed from one organism to another.
What are the types of pathogens?
bacteria, viruses, protozoa, fungi and parasites
what is bacteria
-single cell prokaryotic organism
-They have a cell wall but no membrane, bound nucleus or organelles.
-Their genetic material is a singular large chromosome, a cellular thread of DNA, double helix
-Causes Food poisoning, Ear and eye infections and cholera, diarrhea
what are virus’
-acellular pathogens
-have both living and non-living characteristics. –They contain genetic material and are able to pass on hereditary information (a characteristic of living organisms),
-are not composed of cells and can be crystallised (characteristics of non-living things). -made up of a protective protein coat that encloses the genetic material, which may be either DNA or RNA. Viruses that contain RNA are known as retroviruses.
-Viruses are larger than prions and many times smaller than bacteria.
what is Fungi?
Fungi are eukaryotic organisms that possess a cell wall, but its composition is different to that of plant cell walls.
Do not contain chlorophyll and are not capable of producing their own food
Both unicellular such as yeasts and multicellular like mushrooms
most are composed of a system of microscopic tubular filaments or threads known as hypae which branch and spread to form a structure known as a mycelium
what are parasites (protozoans)?
protozoans are single celled eukaryotic organisms.
Cell membrane, cell wall and posses a membrane bound nucleus and membrane bound organelles.
many are free living and do not cause disease but some are pathogenic and cause malaria, Leishmaniosis and toxoplasmosis
what size are virus’
They range in size from 30 to 300 nm and can only be viewed using an electron microscope. A nanometre is one billionth of a metre.
what size is bacteria
They are larger than viruses, but smaller than protozoans and vary in size from 0.5 to 100um (1mm = 1000um)
what causes diseases
environment, genetics and lifestyle
What are the lines of defence
1st line of defense is barriers to prevent infection like liquids skin and hair
2nd line of defense general response to infection such as inflammation, phagocytes, blood clotting
3rd line of defense immunity against specific pathogens such as lymphocytes, antigens, antibody’s
What is adaptive immunity
when your body cells remember the pathogen so it can fight the disease when it comes.
what is herd immunity
when a large portion of people become immune to a disease
