infection and response Flashcards
what are the 4 microorganisms
bacteria
protists
fungi
viruses
what is the definition of pathogens
microorganisms that can cause disease
how do pathogens spread and examples
through air (tiny droplets we expel from coughs or sneezes)
eg:flu or measles
through contaminated food or water
eg:cholera or salmonella
what pathogen is spread by direct contact
athletes foot-spread by walking bare foot on contaminated surfaces
how do we stop diseases spreading
improved hygiene
killing vectors(organisms that transport pathogen)
vaccinations
quarantine
how do viruses colonise and make us feel ill
they get inside an organisms cell and use it to clone themselves and burst it making us feel ill- the viruses will spread finding new cells to colonise which is why we feel ill
explain what causes measles/symptoms
causes red rash and fever
-can be fatal
spread by infected persons coughs or sneezes
what causes hiv and symptoms an d treatments
exchange of bodily fluids(eg blood) and sexual contact
-causes deficient immune system
-fever tiredness and aches for the first few weeks
-when immune system really begins to weaken they can develop aids disease(symptoms can be
unusual infections or cancers
-antiretroviral drugs
if people have taken early on in disease it prevents virus replicating allowing people to live normal lives
what causes tmv/symtoms
affects tobacco or tomato plants
-causes discoulored patches on leaves causing mosaic pattern
photosynthesis cant take place in the discoloured patches so plant cant make enough sugars for sufficient growth
how do bacteria make us feel ill
they have good food supply in our bodies
they produce toxins which damage our cells/tissues
what is salmonella/symptoms and treatments
bacteria that causes food poisoning from any food that has the bacteria
-mostly got from chickens who had it when they were alive
most chickens are vaccinated
-causes fevers/stomach cramps/ vomiting and diahrea
passes with in a week/must stay well hydrated
what is gonohrea an example of /how is it spread/treatments/prevention
a bacterial std that is spread from sexual contact
-symtoms are pain when urinating and a thick green or yellow discharge from penis/vagina
-stopped by using barrier methods/avoiding unsafe sex
-use penicillin(many strains have become resistant) or nowadays rarer more expensive antibiotics
what is rose black spot /its symptoms /treatments
-fungal disease that causes purple/black spots to form on leaves of plants
leaves turn yellow and drop off
less leaves to get food via photosynthesis and therefore plant does not grow so well
-spreads via water or wind
-treated by chopping off infected leaves and burning
or
spraying plants with fungicides
what is malaria /symptoms/causes and treatments
caused by a parasitic protist-which needs a host to survive(eg:human)
-transported between hosts by vectors(mosquito)
spread by mosquitos that feed on infected animals blood and gets malaria parasite and transfers them to healthy host when feeding on them
-symtoms
fevers
headaches
these are callled recurrent episodes if they keep coming back
-prevented by stopping vectors spreading protists
(eg:killing with insecticides/destroying breeding sites/using mosquito nets or repellents)
what is a physical defence against pathogens and what happens when they cant enter
skin-pathogens cant get through as it is a physical barrier
it secretes oils and anti-microbial substances which kill pathogens that rest on it
-pathogens that cant get through try to get in through mouth and nose
what is a physical/chemical barriers against pathogens
-nose has lots of hairs and mucus which traps pathogens and other particles that try to float through in the air
-if they get through the trachea , bronchi and bronchiole have mucus layer which traps any particless
-there is also enzymes in tears
what are the 2 ways the body can defend itself against pathogens
-physical and chemical barriers
-the immune system
what is the role of cilia and how does it link to the stomach
tiny finger like structures that protrude from the trachea cells and rythmically move to waft mucus and trapped particles to the back of the throat where we can swallow it down to the stomach which is ph 2 and kills most pathogens
what are 3 functions of white blood cells
phagocytosis
producing antitoxins(tiny poisons which damage cells)
produce antibodies
what are antigens
any substance the body detects as being foreign(eg cell wall of bacteria)
what is phagocytosis
process where white blood cells engulf pathogens by tracking, binding and engulfing them and after this can destroy them
explain the use of antibodies
antibodies are small proteins made by wbc that can lock on to these foreign antigens and act as signals telling wbc to come and destroy them
-they can only bind to one antigen(specific)
how do antibodies link to the term immune
when the immune system knows which antibodies can bind the pathogen it produced a lot of them and in the future our body will produce so many antibodies the pathogens will be destroyed before they can develop
how do vaccines work
contains dead or weakened antigens which triggers our bodies to produce antibodies
-they can work against viruses and bacteria
pros and cons of vaccine
pros
-protect us from diseases
-control common disease
-prevent (epidemics)
cons
-dont always work(full immunity)
-bad reactions(side effects)
what is herd immunity
when enough people in a population are immune to the pathogen it wont have people to spread to
then when the host overcomes the disease or dies the pathogen dissapears
what are the 2 types of medications
-relieve the systems(eg:painkillers like paracetomol/aspirin)
-treat the disease(eg antibiotics)
why cant antibiotics work on viruses
made specifically to work on bacteria
they wouldnt be able to find viruses as they hide in between our body cells
what do antibiotics do to bacteria that painkillers cant
they directly kill or stop bacteria growing in throat
but with painkillers these pathogens would still be there
what could help to reduce the spread of antibiotic resistance?
Doctors only prescribing antibiotics for serious bacterial infections
Patients taking antibiotics for the full prescribed course
what is an example of a drug found in nature
-aspirin found in the bark of willow trees
-penicillin found /released by fungus which killed colonies of bacteria in a petri dish
what are the factors we need to test new drugs
efficacy-how well it works/gives the effect you want
eg(antibiotic at killing bacteria)
toxicity-(how harmful it is )eg side effects
dosage-how much of the drug
what links dosage with the toxicity/efficacy of a drug
the higher dosage the more efficacy and more toxicity(side effects)
what are the stages of drug testing
preclinical testing with human cells and tissues
preclinical testing with live animals mammals like mice
then clinical testing
explain the 1st stage of drug testing
+pros and cons and what happens if the substance looks promising
1)drug is tested on lab grown human cells and tissues
-easy and cheap
-doesnt tell us much on how it affects whole organism/particular organ
we move on to stage 2 if the substance looks promising
explain stage 2 of drug testing and what it tells us about overall effect of the drug
1)testing on live animals
-similar to human bodies
-tells us efficacy and toxicity of drug
explain stage 3 of drug testing
1)give drug to healthy volunteers at a low dose
2)slowly increase dose doctors closely monitoring the health of the volunteers(checking for any side effects) to see the max dosage we can give before we start to get side effects
3)give to people suffering and repeat this looking for the optimum dosage(where the efficacy is max and toxixity is minimised)
how do we keep these trials fair
-should be blind
-use a placebo
double blind trials
-give half real drug and half placebo so there is no unconscious bias and fake side effects
-peer reviewed by other scientists
Why is it important for medical trials to be double-blind?
To avoid any bias by the patients and/or researchers
If patients know they received the drug they may be more likely to report side effects
If researchers know who has been given the real drug then they may pay closer attention to those patients
what are monoclonal antibodies
antibodies from a single clone of cells made in labs
how do we form monoclonal antibodies
B-lymphocyte cells combine with fast dividing tumour cells to form a hydbridoma which produce antibodies but also divides rapidly which clone producing identical antibodies
how do we get b-lymphocyte
inject mouse with antigen and it will produce antigen specific antibodies
steps to produce monoclonal antibodies
Inject an animal, like a mouse, with the antigen that we want our antibodies to bind to.
Let the animal develop an immune response, and then isolate some of their B-lymphocytes (which will produce the antibody we want).
Combine those B-lymphocytes with fast-dividing tumour cells to form hybridoma cells.
Let these hybridoma cells divide rapidly in a petri dish.
Collect and purify the monoclonal antibodies they produce
why are pregnancy tests used
they are cheap,quick and reliable way to see if a woman is pregnant
what are nitrates needed for
for making proteins-so for growth so deficiency causes stunted growth
how can plants catch diseases
1)from micro-organisms(bacteria)
2)larger organisms(insects)
3)from deficiencies(nitrate/magnesium)
what are magnesium ions needed for
making chlorophyll so for photosynthesis so deficiency will cause chlorosis (have yellow leaves)
what are some other 4 forms of symptoms diseased plants may have
-abnormal lumps/growths
-patches of decay
-decolouration on leaves
-malformed stem/leaves
how can you diagnose disease
send sample of diseased plant to a plant pathologist
or
trial and error
eg; give magnesium if u think its a magnesium deficiency
what are the 3 types of plant defences
physical
chemical
mechanical
what are some examples of physical defences in a plant
waxy cuticle
cellulose cell walls
dead cells some plants like bark have around stems
what are some chemical defences a plant may have
-anti microbial substances to kill bacteria or fungi
-poisons that kill insects
what is the meaning of mechanical defences and what are some mechanical defences a plant has
physical defences with a function rather than just a barrier2
-thorns or hairs that stop animals touching or eating them
-leaves that curl or droop if insects land pn them
-Mimicking other organisms to trick animals
Give 5 ways in which plant diseases can be identified.
Compare the symptoms to a gardening manual or website
Take the infected plants to a laboratory (plant pathologist) to identify the pathogen
Use testing kits that contain monoclonal antibodies
Test the DNA of the pathogens
Use trial and error to test different treatments
