Pathogens 12.1 Flashcards
Communicable Disease
A disease that can be passed on from one organism to the other and is normally caused by infective organisms called pathogens
Pathogen Types
Bacteria, fungi, viruses, protoctista
Vectors
These will carry pathogens from one organism to another without being affect itself. Examples include mosquitos and water
Bacteria
These are living prokaryotes so have a cell structure that is very different to the organism it infects. It has no membrane bound nucleus or organelles
How can you classify a bacteria?
Look at it’s shape, it can be rod, spherical, comma, spiral or corkscrew shaped
Look at it’s cell walls and do a gram staining test. Some bacteria are gram positive like MRSA, some are gram negative like E.coli
Viruses
Viruses are non-living infectious agents that normally exist as some genetic material surrounded by a protein. They take over the hosts cell and override the genetic material to start reproducing rapidly as well as adapt and mutate to stay alive and take over the cell which makes them very successful pathogens. There are also bacteriophages that can take over bacteria and kill them and these are used in medical research.
Protoctista
These are single celled eukaryotic organisms that can cause devastating communicable diseases. They are parasitic so live off their host and may need a vector to pass them on. An example is malaria
Fungi
Fungal diseases are a main problem in plants. Fungi are multicellular eukaryotic organisms. They digest their food extracellularly and don’t photosynthesise. There are many parasitic fungi that feed off of their host organism, for example feeding off a plant which will damage them and stop them photosynthesizing so will kill them quickly. When they reproduce they produce tiny spores which can spread very far so can infect very long distances very rapidly.
Why do you actually get ill from a disease?
You get ill because of how the pathogen is damaging your tissue and also how your body is fighting the damage and the pathogen.
How do viruses attack?
They take over the cell metabolism and its viral genetic material is injected into the hosts DNA which will start replicating more viruses which destroys the cell and the virus will start infecting other cells.
How do protoctista attack?
They also take over cells and break them open, but they don’t take over the DNA, they only take the cell contents and use it to reproduce.
How do fungi attack?
They just digest living cells and destroy them. Some produce toxins which affect the cells
How do bacteria attack?
They can produce harmful toxins that either break down the cell membrane and damage cells or inhibit some enzymes or interfere with genetic material so cells cannot replicate.
