bacteria Flashcards
bacteria structure
- cell membrane
- cytoplasm
- ribosome
- capsule
- plasmids
- cell wall
how does bacteria cause disease
- bacteria enters the host
- bacteria divide / reproduce rapidly via binary fission in the host
- bacteria damages the body directly by reproducing in the host tissue and directly through the production toxins
virus structure
- very small / microscopic
- non-cellular
- capsid
- nucleic acid
- viral envelope
- surface proteins
virus
- non-cellular pathogen that can only reproduce inside a living host
fungus structure
- eukaryotic
- ribosomes, cytoplasm
- membrane bound organelle
spore production
- most fungi are able to reproduce sexually and asexually by producing spores
- spores develop into new organisms without the fusion of gametes
- when one of these microscopic spores lands in suitable conditions it produces fungi
protist
diverse group of eukaryotes that are usually unicellular and live in water
protist structure
- eukaryotic cell
- unicellular
- microscopic
- cilia
- flagellum
- cell wall
antigenic drift
- a minor change to a virus, can lead to changes in surface proteins
- small changes may accumulate and cause a minor change
eg influenza A and B
antigenic shift
- major change
- occurs when two viruses cross
- when the virus mutates they shift to create a new subtype that is different
lytic cycle
- virus attaches to the cell membrane of the host cell
- the virus injects its nucleic acid into the host cell
- the viral nucleic acid then takes over the host cell and directs it to make multiple copies of the viral protein coat and nucleic acid
- these assemble into new viruses and released when the host cell undergoes lysis
- the released viral particles then inject other cells in the host, cell lysis (cell bursts)
mode of transmissions
- direct contact
- indirect contact
- vectors
- soil/water/food transfer
direct contact
diseases are spread through direct host to host contact through bodily fluids / sexual transmission
indirect contact
can be spread through airborne droplet transmissions where the pathogen is expelled from the respiratory centre by coughing or sneezing
vectors
transfer by a living organism the disease can only be spread in areas where the vector is present
soil / water / food transfer
transfer through contact with contaminated soil or ingestion of contaminated food or water
active immunity
natural active: immunity due to suffering from the disease, the ability to manufacture antibodies
artificial active: immunity due to a vaccine
passive immunity
natural passive : antibodies enter the bloodstream across the placenta or in breastmilk
artificial passive: antibodies are injected into the bloodstream eg when exposed to rabies antibodies are given so that immunity is established immediately
endemic
a disease that is always is present at predictable levels in a population or region
outbreak
a sudden unexpected increase in the prevalence of a particular disease in a local area
epidemic
a sudden increase in the prevalence of a particular disease in a local area
pandemic
the rapid spread of a particular disease throughout the world, an epidemic that crosses an international border
herd immunity
the resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease
principles of herd immunity
- immunity is usually gained by an artificial vaccine causing the formation of specific antibodies and memory cells abasing a pathogen
- this limits the spread of the disease as there are too few susceptible hosts. the pathogen population cannot reproduce at a high enough rate to maintain the population
- infected hosts carrying the pathogen are more likely to come into contact with immune individuals reducing the possibility for transmission
- the higher the proportion of immune individuals the greater the protection
- this protects those who cannot be vaccinated such as those with allergies, pregnant women
