infection and response Flashcards
pathogens
microorganism that cause infectious disease in plant or animals spread through direct contact, by water or air
virus
- very small
- move into cells and uses biochemistry of it to make copies of itself
- leads to cell bursting and releasing copies into bloodstream
- damage and destruction of cells make individuals feel ill
- live and rapidly reproduce inside cells, causing cell damage
bacteria
- small
- multiply very quickly through binary fission inside body
- produce toxins that can damage tissues and make us feel ill
protists
- some are parasitic meaning they use humans and animals as their hosts (live on and inside causing damages)
fungi
- can either be single celled or have a body made of hyphae
- can produce spores which can be spread to other organisms
direct contact
- touching contaminated surfaces
- e.g kissing, contact with bodily fluids, skin to skin
by water
- drinking or coming into contact with dirty water
by air
- pathogens carried in the air then breathed in
- common example is the droplet infection when sneezing, coughing or talking expels pathogens in droplets that can be breathed in
improving hygiene
- hand washing
- using disinfectants
- isolating raw meat
- using tissues
- handkerchiefs when sneezing
reducing contact with infected individuals and reducing vectors
- using pesticides or insecticides and removing their habitat
vaccination
by injecting a small amount of a harmless pathogen into an individuals body, they can become immune to it so it will not infect them and they cannot pass it on
viral diseases
- particularly dangerous as they can enter all types of cells, no medicine yet
- measles
- human immunodeficiency virus (HIV)
-tobacco mosaic virus
measles
SYMPTOMS
- fever, red skin rash, can lead to other problems e.g pneumonia, encephalitis (brain infection) and blindness can be fatal if complications continues
HOW IT IS SPREAD
- droplet infections
HOW IT IS PREVENTION
- vaccinations for young children to reduce transmission
HIV
SYMPTOMS
- initially flu-like symptoms then virus attack the immune system and leads AID (a state in which the body is susceptible to many different diseases)
HOW IT IS SPREAD
- by sexual contact or exchange of bodily fluids e.g blood when drug users share needles
HOW IT IS PREVENTED
- the spread = using condoms, not sharing needles, screening blood when it is used in transfusions
- development of AIDs - use of antiretroviral drugs (stop the virus replicating in the body)
tobacco mosaic virus
SYMPTOMS
- discolouration of the leaves, affected part of the leaf cannot photosynthesise resulting in the reduction of the yield and affects growth, distinctive mosaic pattern
HOW IT IS SPREAD
- contact between diseased plants and healthy plants, insects act as vectors
HOW IT IS PREVENTED
- good field hygiene and pest control, growing TMV-resistant strains
bacterial disease
- on the rise as they are becoming resistant to antibiotics
salmonella
SYMPTOMS
- fever, stomach cramps, vomiting, diarrhoea (caused by toxins secreted)
HOW IT IS SPREAD
- found in raw meat and eggs, unhygienic conditions
HOW IT IS PREVENTED
- poultry vaccinated against it, keeping raw meat away from cooked food, avoid washing it, wash hands and surfaces when handling, cook food thoroughly
gonorrhoea
SYMPTOMS
- thick yellow or green discharge from vagina or penis, pain when urinating
HOW IT IS SPREAD
- sexually transmitted disease spread through unprotected sexual contact
HOW IT IS PREVENTED
- using contraception
- before penicillin but many resistant strains are developing
rose black spot (fungal disease)
SYMPTOMS
- purple or black spots on leaves of rose plants, reduces the area of the leaf available for photosynthesis, leaves turn yellow and drop early
HOW IT IS SPREAD
- spores of fungus are spread in water (rain) of by wind
HOW IT IS PREVENTED
- using fungicides or stripping the plant of affected leaves (have to be burnt)
malaria (protist)
SYMPTOMS
- fevers and shaking (when the protists burst out of blood cells)
HOW IT IS SPREAD
- vector is the female anopheles mosquito, in which protists enter the human bloodstream via their saliva
HOW IT IS PREVENTED
- using insectide coated insect nets while sleeping, removing stagnant water to prevent the vectors from breeding, travellers taking antimalarial drugs to kill parasites that enter the blood
non-specific defence system
works to prevent pathogens from entering the body
skin
- acts as a physical barrier
- it provides antimicrobial secretions to kill pathogens
- good microorganisms known as skin flora compete with the bad microorganisms for space and nutrients
the nose
- has hairs and mucus which prevent particles from entering your lungs
trachea and bronchi
- secrete mucus in order to trap pathogens
- cilia beat to waft mucus upwards so it can be swallowed
stomach
- produces hydrochloric acid that kills ant pathogens in your mucus or food and drink
specific immune system
- acts to destroy any pathogens which pass through the non-specific immune system to the body
- large part is white blood cells
phagocytosis
- engulfing and consuming pathogens
- destroys them meaning they can no longer make you feel ill
producing antibodies
- each pathogen has an antigen on their surface, a structure which a specific complementary antibody can bind to
- once antibodies begin to bind to pathogen, pathogens clump together resulting in it being easier for white blood cells to find them
- if infected with the same pathogen again the specific complementary antibodies will be produced at a faster rate
- individual will not fell symptoms of illness and are said to be immune
producing antitoxins
- neutralise the toxins released by the pathogen binding to them
vaccinations involve making an individual immune to a certain disease..
they are protected against it before they have been infected
herd immunity
immunising a large proportion of the population, the spread of the pathogen is reduced as there are less people to catch the disease from
vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body…
to stimulate white blood cells to produce antibodies, if the same pathogen re-enters the body the white blood cells respond quickly to produce the correct antibodies preventing infection
advantages of vaccination
- eradicated many diseases so far e.g smallpox
- reduced the occurence of many e.g rubella
- epidemics can be prevented through herd immunity
disadvantages of vaccinations
- not always effective in providing immunity
- bad reactions can occur in response to vaccines although very rare
antibiotics
- e.g penicillin
- help to cure bacterial disease by killing infective bacteria inside the body without damaging body cells
- important specific bacteria treated by specific antibiotics
- cannot kill viruses as they use body cells to produce, meaning any drug that target them would affect body tissue too
painkillers
e.g aspirin only treat the symptoms of the disease rather than cause
what way can antibiotics be taken?
- a pill
- a syrup
- directly into the bloodstream
use of antibiotics has…
greatly reduced deaths from infectious bacterial diseases however emergence of strains resistant to antibiotics is a great concern
concern of bacteria becoming resistant to antibiotics
- mutations can occur during reproduction resulting in certain bacteria being killed by antibodies
- when these bacteria are exposed to antibiotics only non-resistant ones die
- resistant ones survive and reproduce, meaning population of resistant bacteria increases
- means previously effective antibiotics no longer work
we can prevent the development of resistant strains by…
- stop overusing antibiotics - unnecessarily exposing bacteria to the antibiotics
- finishing courses of antibiotics to kill all of the bacteria
new drugs must be tested for…
- toxicity, efficacy (how well they carry out their role) and dose, using preclinical testing and clinical trials
plants (discovery and development and drugs)
- chemicals plants use to kill pests and pathogens an be used to treat symptoms or human disease
- e.g aspirin as a painkiller (willow), digitalis used to treat heart problems (foxgloves)
microorganism (discovery and development of drugs)
- penicillin = alexander flemming growing bacteria on plates, found mould on culture plates with clear rings around mould indicating there was no longer any bacteria there, found mould was producing a substance called penicillin which killed bacteria
preclinical testing
- using cells, tissues and live animals
testing process
- first tested on healthy volunteers with a low does to ensure there are no harmful side effects
- drugs tested on patients to find most effective dose
- to test it efficacy patients split into two groups
- one group receiving drug and one receiving placebo (looks like og but has no active ingredient so no effect) so the effect of new drug can be observed
- can be single-blind (only doctors know) or double blind (neither patient or doctor knows, removing any biases doctor may have when recording results)
clinical testing
- using volunteers and patients
why do the results need to be peer reviewed?
to check for repeatability
monoclonal antibodies
- identical antibodies that have been produced from the same immune cell
- as a result of their ability to bind to only one protein antigen they can be used to target chemicals and cells in the body so have many different medical uses
how are monoclonal antibodies produced?
- mice lymphocytes (make antibodies but cannot divide) obtained, have been stimulated to produce a specific antibody
- then combined with tumour cells (do not make antibodies but divide rapidly) to form a cell called a hybridoma
- hybridoma can divide to produce clones of itself, which all produce the same antibody
- antibodies are collected and purified in a lab
uses of monoclonal antibodies
- pregnancy tests
- in labs to measure and monitor hormones and chemical levels in blood
- in research to find or identify certain molecules on a cell or tissue
- in the treatment of disease e.g cancer
pregnancy tests
- hormone called human chorionic gonadotrophin (hCG) present in urine of women who are preggo
- two sections in stick
- first has mobile antibodies complementary to hCG hormones, antibodies also attached to blue beads
- second has stationary antibodies complementary to hCG hormone which are stuck down to the stick
- individual urinates on first section, if hCG present binds to mobile antibodies to form hCG/antibody complexes
- carried in flow of liquid to second section
- stationary antibodies bind to hCG/antibody complexes
- since they are bound to blue bead it results in a blue line which indicates you are preggo
labs to measure and monitor
- levels of hormones or chemicals in blood
- monoclonal antibodies modified so only bind to molecule your looking for
- antibodies also bound to fluorescent dye
- if molecules are in sample then antibodies bind to it and dye can be observed
-e.g screening donated blood for HIV infections
research to find certain molecules on a cell or tissue
- same as measuring and monitoring
- look for build up of fluorescence
treatment of disease e.g cancer
- cancer cells have antigens on their cell membranes aka tumour markers, which can be targeted
- 3 main ways to treat
1. producing monoclonal antibodies that bind to tumour markers to stimulate the immune system to attack cell
2. using monoclonal antibodies to bind to receptor sits on the cell surface membrane of the cancer cells meaning growth-stimulating molecules cannot bind, stopping the cells from dividing
3. using m.a to transport toxic drugs, chemicals or radioactive substances as they can only bind to cancer cells
advantages of using monoclonal antibodies
- only bind to specific cells, meaning healthy cells are not affected
- can be engineered to treat many different conditions
- now able to produce mouse-human hybrid cells to reduce the chance of triggering an immune response
disadvantages of using monoclonal antibodies
- difficult to attach monoclonal antibodies to drugs
- expensive to develop
- as they were produced from mice lymphocytes often triggered an immune response when used in humans
common signs of plant disease
from viral, bacterial and fungal pathogens
stunted growth
indicates nitrate deficiency
spot on leaves
indicating black spot fungus on roses
area of decay
black spot fungus on roses, blights on potatoes
abnormal growths
crown galls caused by bacterial infection
malformed stems or leaves
due to aphid infestation
discolouration
indicating magnesium deficiency or tmv
pests on leaves
e.g caterpillars
can identify disease the plant has by
- using a gardening manual/website
- identifying the pathogen by observing the infected plant in a lab
- using monoclonal antibodies in testing to identify pathogen
nitrate deficiency
- can stunt growth
- nitrates in soil convert sugars made in photosynthesis into proteins (protein synthesis)
- these proteins are needed for growth
magnesium deficiency
- can cause chlorosis
- magnesium need to make chlorphyll
- pigment is green and vital in photosynthesis
- less chlorophyll = some parts of leaves appear green and yellow
physical plant defences
- prevent invasion of microorganisms
- tough waxy cuticle stops entry into leaves
- cellulose cell walls form a physical barrier into cells
- plants have layers of dead cells around stems e.g bark which stop pathogens entering dead cells fall off with pathogens
chemical defences
- to deter predators or kill bacteria
- poisons e.g foxgloves, tobacco plants, deadly nightshades, yew to deter herbivores
- antibacterial compounds kill bacteria e.g mint plant and witch hazel
mechanical defences
- thorns and hairs make it difficult and painful to eat them
- some leaves can droop/curl when touched, allowing them to move away insects off their leaves
- mimicry to trick animals e.g droop to appear unhealthy, patterns to appear like butterfly eggs
