Antigens and pathogens Flashcards
antigens
molecules that interact with the cells of the immune system, they are capable of inducing an immune response
what are the two types of antigens
self and non-self
self antigens
antigens located on the surface of cells that originate from the organism
what is the purpose of self-antigens
marks the cells of the organism as self which prevents the immune system eliciting a response against the, important self antigens can take the form of MHC proteins
MHC proteins stand
major histocompatiubilty complex proteins
what are MHC I proteins
proteins expressed on all nucleated cells (i.e. not red blood cells)
what are MHC II proteins
proteins found on specialised cells of the immune system
how are MHC proteins formed
each MHC marker contains a degraded peptide (part of a degraded protein) that was bound to it inside of the cell. The MHC marker is then moved to the plasma membrane abd presents it peptide on the surface
self vs non-self
self means cells and molecul;es that make up ur own body, non-self is anything else
non-self antigens
marks a cell/pathogen as forgein to the organism, proteins on the cells surface will induce an immune response
autoimmune disease
when the cells of the immune system incorrectly identify self antigens as non-self antigens and illicit an immune response
what determines the blood type of an individual
the surface proteins found on their red blood cellst
type o blood antibodies and antigens on red blood cells
antibodies; anti A and anti B, antigens: none
type A blood antibodies and antigens on red blood cells
antibodies; anti b, antigen; antigen a
type B blood antibodies and antigens on red blood cells
antibodies; anti a antigen; antigen b
type AB blood antibodies and antigens on red blood cells
antibodies; none antigens; antigen A and antigen B
why can a person with A type blood donate to a person with B type blood and vis versa and why cant o type blood recieve AB A and B
the B/A antigens on the blood surface will be recognised as non-self and will trigger as immune response due to anti b/anti a antibodies
why can o group dopnate tpo anybody
there are no markers on their red blood cells top recognise as non-self
can type AB recieve anthing
yes as they have no antibodiesd that will react with the A/B antigensd
what are the cellular pathogens
bacteria, fungi and protozoa - all unicellular, ticks and worms - all multicellular
what are the non-cellular pathogens
virus and prions
what is a pathogen
the causative agent of an infectiopus disease
structure of bacteria
prokayotic, contain a cell wall, use binary fission to reproduce, contain flagella to move
why do bacteria infect
to gain nutrients from the host
when food supply runs low, bacteria form…
spores which can survive non-ideal conditions and varying temps
what makes bacteria toxic/pathogenic
when they release exotoxins and/or endotoxins and/or enzymes which either affect the functioning or cells or kills the cells
exooxins
toxic compound released by bacteria into their environment and carried through the blood stream, more harmful
endotoxins
toxic compound apart of the exterior wall of gram negative bacteria, is released when bacteria dies, lees harmful as contained within a cell until that cell dies
gram negative bacteria
contain a lipid coat so doesnt release toxins but when it dies, toxins are released
how bacteria can be transmitted
contaminated food/water, touching, droplets in the air
bacterial infection treatment
antibiotics - can be determined which antibiotic will be effective against the specific type of bacteria through sensitivity testing
how do antibiotics work
interfering with the making of the bacterial cell wall, some stop production of important chemicals/ proteins needed by the bacteria by interrupting translation, some interefere with the genetic material of the bacteria, causing it to stop dividing
rod shaped bacteria are called
bacillus
sphere shaped bacteria are called
coccus
spiral shaped bacteria are called
spirillus
how does sensitivity work/what happens
discs of antibiotics are placed in agar that is infused with the bacteria, the size of the zone of inhibition (no bacteria growth) determines the effectiveness of the antibiotic
bacterial infection prevention methods
antisectips and disinfectant
disinfectantt
a chemical agent that destroys, neutralises or inhibits the grow of microorganisms on non-living surfaces
antisectics
a chemical agent that kills or inhibits the growth of microorganisms on the external surface of the body
what bbacteria are non-pathogenic
many are beneficial including species that live in the gut and/or intestine and help with digestion
fungi structure
contain a cell wall different to prokaryotes and plant cells, eukaryotic, can be unicellular or multicellular, contain long branching filaments called hyphae
hyphae
long extensions found on fungi that develops specialised structures that produce asexual spores via mitosis
how does fungi infect humans
infect the skin, nails and hair and can also produce toxins
how does fungi infect plants
usually only in one area of the plant,
fungi harm in plants vs human
more harmful in plants, most fungal diseases in humans are non-life threatening unless they are immuno compromised
how is fungi transmitted
contact with an infected person, contact with spores which are transferred through the air
how if fungi treated
fungicide
fungicide
kills or inhibits the fungus or the fungal spores
protista structure
unicellular, eukaryotic, can produce a capsule called a cyst to avoid drying out and to survive in harsh conditions
what protista is harmful
not all, those that are may inhibit nucleaic acid synthesis or/and protein synthesis or/and various stages of cellular respiratipn
how is protista transmitted
through a vector, contaminated water
examples of multicellular pathogens
ticks, mites and worms
parasite
fall under multicellular pathogens, an organism that lives on or in another organism (host) and takes resources from the host to its detrement
multicellular pathogens have adaptations to
survive in the hermaphrodite, piecrcing parts and more than one host in a lifetime; can produce many eggs, have hooks and suckers
primary hosts
where the adult produces eggs/gametes, parasite matures to adult stage, sexual reproduction may occur
two types of hosts
primary host and intermeidate host
intermediate host
where an immature parasite develops, but not to sexual maturity
two types of parasites
ectoparasites and endoparasites
ectoparasite
found on and affect the outside of tthe body e.g. ticks
endoparasite
found on and affect the inside of the body e.g. tape worm
structure of a virus
contain DNA or RNA surrounded by a protein coat (capsid),some viruses have a phospholipid memebrane surrounding the capsid, have glycoproteins on the outer envelope, which are specific to the virus and are recognised as antigen markers
how can viruses be transmitted
water droplets in air, saliva, bodily fluid, insect vectors
how are viruses classified
by the type of nucleaic acid they have and the different structures that make up the envelope
what is the general process of a virus infecting a cell
virus comes into contact with host cell, attaches to host cell, inserts its own genetic material, infected host begins to follow the genetic materials instructions producing viral protein and more genetic material, some viruses remain dormant inside the host cell for a very long time, once the host cell bursts, it releases the virus and all copies made and then dies
what are the two types of viruses
positive sense and negative sense
what are retroviruses
viruses that insert negative sense rna intoo the host
how do retroviruses replicate
insert negative sense rna into the host, enzymes transcribe it backward into dna and intergrate it into the cells genome
how to positive sense rna viruses replicate
their rna is inserted into the cell but does not get reverse transcribed into DNA, it is read directly by tRNA
how are viruses treated
through antiviral drugs
how do antiviral drugs work
can block protein synthesis and///or bind to receptors on the virus that are designed to detach from the host cell and/or bind with host cell receptors blocking the area where the virus would attach
why are antiviral drugs difficult to design
because the virus uses a host cell and it is difficult to design a drug that doesn’t harm the organisms cells
what does HIV stand
Human immunodeficiency Virus
how is HIV transmitted
through blood, breat milk, sharing needles, semen or vaginal fluids, most commonly through unprotected sex
what are the effects of HIV
damages the immune system by infecting helper t cells, macrophagges and other immune system cells, initiates apoptosis in unaffected bystander cells, destroys host cells after using them, can lead to aid (final stage of HIV infection)
AIDS stands for
acquired immunodefifiency syndrome
what are prions
misfolded proteins that have lost their fuunction, occur in neural tissue
how do prions arise
cells have the gene/s to make the normal prion protein, however a mutation to that gene results in an infectious protien
how/how is a prion harmful
prion protein has an unusual shape which allows it to bind to the normal prion protein, the normal prion protein is then converted into an infectious protein, they then do convert normal nearby proteins whilst remaining attached, the infectious prion protein accumulates, forming a long filament, causing the cell to burst
how are prions transmitted
eating contaminated meat, contaminated surgical equipment
what are the methods to controlling the spread of pathogens
personal hygiene, condoms, quarantine, cleaning up the environment, sanatation, immunization, disinfectants and sterilisation
