infection and response (T3) Flashcards
what is a communicable disease
a disease caused by a pathogen which can be passed between animals or plants e.g. flu
what is a pathogen
a disease causing-microorganism
what are the 4 types of pathogen
virus, fungi, protist. bacteria
how do bacteria cause disease
once inside the body they divide rapidly by binary fission. they kill cells and produce harmful toxins
how do viruses cause disease
hijack cells and reproduce until the cell bursts causing damage
ways in which pathogens can be spread
by air- flu, tb, cold (droplet infection)
by water - cholera, fungal spores spread plant diseases
by touch - cold sores
by food - food poisoning E.Coli 0157
blood - hepatitis
sexually transmitted - chlamydia
insect borne - malaria
ways in which the spread of pathogens by air can be reduced
- covering mouth when you sneeze or cough
- wearing a mask
ways in which the spread of pathogens by touch can be reduced
- washing hands
- isolation
ways in which the spread of pathogens by food can be reduced
- cook food properly
- clean well
- good cooking hygiene
ways in which the spread of pathogens by water can be reduced
- sterilise water - boil it
- drink clean water
ways in which the spread of pathogens by blood can be reduced
- don’t share needles
- get blood checked
ways in which the spread of pathogens by sexual contact can be reduced
- barrier method of contraception e.g. condoms
ways in which the spread of pathogens by insects can be reduced
- mosquito nets
- insect repellant
why is it especially important to reduce the spread of viral diseases
scientists have not yet developed cures for many viral diseases
what is measles
serious viral diseases that can lead to blindness and brain damage.
what are the main symptoms of measles
fever, red skin rash
how is measles spread
by air - inhalation of droplets from coughs and sneezes
what is HIV/AIDS
virus which attacks and damages the immune system until it can no longer function properly. AIDS is the condition resulting from a long term HIV infection. there is no cure.
how is HIV spread
direct sexual contact and exchange of bodily fluids eg. blood, breastmilk
symptoms of HIV
- AIDS
- herpes or cold sores
- short flu-like illness but can feel well for a long time
- weight loss
- night sweats. thrush in the mouth
how to reduce spread of HIV
- contraception methods
- not sharing needles
treatments for HIV
- anti-viral drugs stop virus replicating
- can have HIV w/o symptoms or transmission to others
treatment for measles
no specific treatment, lots of fluids and rest
what is gonorrhoea
a bacterial infection
how is gonorrhoea spread
- through sexual contact
- from mother to child
symptoms of gonorrhoea
- thick yellow/green discharge
- pain when urinating
how to reduce spread of gonorrhoea
- barrier method
- not having sex
treatments for gonorrhoea
- antibiotic injection
- 500 mg dose
- some gonorrhoea bacteria are becoming resistant to antibiotics
what is salmonella
type of bacteria found in raw meat, eggs and poultry. can affect natural gut bacteria
how is salmonella spread
through the contamination of food
- bacteria ingested in food or on food prepared in unhygienic conditions
symptoms/ effect of salmonella
- diarrhoea
- fever
- headache
- nausea
- abdominal cramps
how to reduce spread of salmonella
- wash hands
- cook food properly
- clean food preparation areas
treatments for salmonella
- does not require treatment
- have lots of water
what is malaria
disease caused by a protist pathogen, carried host to host by a vector (mosquito) which enters the bloodstream and feed.
how is malaria spread
by the bite of an infected female mosquito. carried host to host by a vector (mosquito) which enters the bloodstream and feed.
- can also be spread by blood transfusions or sharing needles
symptoms of malaria
- fever and flu-like, shaking, headache, muscle aches
how to reduce spread of malaria
- destruction of larvae by environmental management
- use of insecticides
- mosquito nets
- removing stagnant water
- malaria tablets
treatments for malaria
- ACT - antimalarial drugs
- no vaccination for it
what type of pathogen is rose black spot
fungus
how is rose black spot spread
fungal spores are carried by the wind and in water
symptoms of rose black spot
- causes purple or black spots to develop on rose leaves.
- turn yellow and drop early so less leaves for photosynthesis so it doesn’t grow and less flowering
how can rose black spot fungus be treated
- using fungicides
- destroying infected leaves
- breeding roses that are resistant
what type of pathogen is tobacco mosaic virus
virus
how is TMV spread
- by contact between diseased plant material and healthy plants
- insects can act as vectors
what are the symptoms of TMV
- distinctive mosaic pattern of discolouration on the leaves which affects growth as it stunts photosynthesis
how to prevent spread of TMV
- good field hygiene and pest control
- can grow TMV resistant plants
how does the skin prevent pathogens from entering the body
- acts as a physical barrier
- scabs forming after skin is cut or wounded
- antimicrobial secretions which can kill pathogens
- healthy skin flora compete with pathogens and act as an additional skin barrier
how does the respiratory system prevent pathogens from entering the body
- nose - has hairs and mucus which traps pathogens
- trachea and bronchi - have mucus that traps pathogens. ciliated cellsmove mucus to the mouth so it can be swallowed
how does the stomach prevent pathogens from entering the body
- secretes hydrochloric acid - kills any pathogens present
how do the eyes prevent pathogens from entering the body
- antibacterial chemicals in tears contain enzymes called lysozymes which destroy microbes
how does phagocytosis prevent pathogens from entering the body
white blood cells (phagocytes) ingest and destroy pathogens so they can’t infect more cells
how does antibody production prevent pathogens from entering the body
white blood cells produce antibodies which are complementary to a specific antigen on a pathogen. the binding of antibodies to antigens causes the pathogens to clump together making them easier to destroy. if there is a second infection, the correct antibodies can be produced rapidly, preventing the person from getting the same disease again
how does antitoxin production prevent pathogens from entering the body
antitoxins bind to toxins released by pathogens and engulf them.
what is a vaccination
a dead or inactivated form of the pathogen which stmulates white blood cells to produce antibodies complementary to the antigens on the pathogen. some of the white blood cells producing the right antibody stays in the blood. if the person catches the disease again these white blood cells or memory cells rapidly multiply and produce lots of the right antibody to fight the disease.
what is herd immunity
if a sufficiently high proportion of a population are immune to a disease (through vaccination) the spread of thedisease will be very limited
advantages of vaccinations
- eradicated many deadly diseases eg. small pox
- many epidemics can be prevented by vaccines
- herd immunity protects those who cannot get vaccines
disadvantages of vaccinations
- not guaranteed to work - might not protect against multiple strains of a pathogen
- may be side effects or adverse reactions
what drugs are used to cure some bacterial diseases
antibiotics
can kill bacterial pathogens in the body
how do antibiotics work
antibiotics e.g. penicillin kill bacterial pathogens inside the body but do not kill human cells, whilst some antibiotics kill a wide range of bacteria it is important that the right antibiotic is used for specific bacteria
why can antibiotics not be used to treat viral diseases
have no effect on viruses as the live inside host (human) cells, difficult to design a drug that will kill virus and not harm human cell at the same time
what is antibiotic resistance
mutations lead to individual bacteria being resistant tk antibiotics. they are able to survive and reproduce passing on their alleles leading to a greater proportion of antibiotic resistance
why is antibiotic resistance concerning
types of bacteria are becoming resistant to all known antibiotics so the diseases cannot be cured
how can we prevent antibiotic resistance
- avoid overuse and unnecessary use of antibiotics
- finish antibiotic courses to ensure all bacteria is killed
what effect do painkillers have on infectious diseases
painkillers can only treat the symptoms but can’t kill the pathogen
what plant is the heart drug digitalis extracted from
foxglove
what painkilelr originates from a compound found in willow bark
aspirin
whant antibiotic was discovered by Alexander Fleming
penicillin
how was penicillin discovered
from a mould
what are 4 qualities of a good medicine
- effective
- safe
- stable
- able to be taken in and removed easily
what 3 main factors are tested when developing a new drug
- toxicity
- efficacy
- dose
how is preclinical testing carried out
- in a laboratory uses cells, tissues and live animals
how is clinical testing carried out
uses healthy volunteers and patients. firstly the drug is tested on healthy people at a low dose then on a large scale to find the optimum dose. often one group get a placebo and the other group get the real drug to test its efficacy
what is a placebo drug
An inactive substance made to resemble a drug for researchers to use as a control.
what is a blind trial (single)
A clinical trial in which the patient does not know whether they are receiving the new treatment but their doctor does.
what is a double blind trial
A medical trial to test a drug in which neither the patient nor doctor know who has the drug and who has the placebo
helps remove bias of a doctor
what is a peer review
where the results of a drug trial are checked over by scientists knowledgeable in the field
what are monoclonal antibodies
- antibodies that are clones of one parent cell
- specific to one type of pathogen
how are monoclonal antibodies produced
1) An antigen is injected into a mouse
2) The mouse naturally produces lymphocytes, which produce antibodies specific to the antigen
3) Spleen cells which produce the lymphocytes are removed during a small operation
4) The spleen cells are fused with human cancerous white blood cells called myeloma cells to form
hybridoma cells which divide indefinitely
5) These hybridoma cells divide and produce millions of monoclonal antibodies specific to the original antigen
what are myeloma cells
type of tumour cell
uses of monoclonal antibodies
- detection of pathogens
- location of cancer cells and blood clots
- treatment of cancer
- used in pregnancy test kits
what do pregnancy test kits test for
HCG hormone in urine
what does a pregnancy test consist of
a stick containing monoclonal antibodies (mABs) specific to hCG:
* mABs attached to a blue bead (free to move)
* mABs fixed to the stick
describe what happems to the stick if the woman is pregnant
- hCG binds to mABs attached to a blue bead
- mAbs with hCG diffuse up the dipstick
- mABS fixed to the stick attach to hCG
- blue line forms
describe what happems to the stick if the woman is not pregnant
no hCG in urine so blue line does not appear
advantage of using monoclonal antibodies to test for pathogens
- specific to one particular antigen
- very accurate
- quick results
why can monoclonal antibodies be used to target cancer cells
- cancer cells have specific antigens called tumour markers on their membranes
- mABs specific to one specific antigen so can be targeted to tumour markers w/o damaging other cells
describe how monoclonal antibodies can be used to diagnose cancer
- mABs tagged to a radioactive substance
- mABs injected into a patient’s bloodstream
- mABs bind to tumour markers on cancer cells
- emitted radiation is detected using a specialised scanner enabling doctors to determine the location of cancer cells
how can monoclonal antibodies be used to target drugs to cancer cells
- mABs attached to anti-cancer drug
- mABS injected into patient’s bloodstream
- mABs bind to tumour markers on cancer cells
- anti-cancer drugs destroys cancer cells
why are cancer treatments that use monoclonal antibodies favoured over traditional treatments
- radiotheraphy and chemotherapy target rapidly dividing cells including healthy cells like hair and bone marrow
- mABs only target cancer cells reducing damage to normal cells
how can monoclonal antibodies be used to locate blood clots
- mAbs tagged to a radioactive substance
- mAbs target and bind to specific proteins in blood clots
- radiation emitted by mAbs is detected enabling the location of blood clots to be identified
how do aphids cause damage to plants
feed off the sugar-rich sap found in the phloem of plants. this deprives the plant of the product of photosynthesis which weakens the plants
how do we reduce the number of aphids
- chemical control - spray them with a pesticide or an insecticide to kill them
- biological control - introduce a natural predator such as ladybirds
why do plants need a good supply of nitrate ions
nitrate is required to convert sugars into protein (protein synthesis) which are required for growth and repair
why do plants need a good supply of magnesium ions
required to synthesise chlorophyll, which absorbs light energy during photosynthesis. as a result the leaves cannot photosynthesise properly and turn yellow (cholorosis)
symptoms of disease in plants
- stunted growth (nitrate deficiency)
- spotted leaves e.g. rbs
- decay/rotting
- growths and tumors
- malformation of stems/leaves
- discolouration (yellow if magnesium deficiency)
- presence of pests
three ways in which plant diseases can be identified
- reference to a gardening website
- taking infected plants to a lab for testing
- monoclonal antibody test kits
examples of physical defences features of plants
- cellulose cell wall - strengthens cell to help resist against pathogens e.g. all plants
- waxy cuticle - acts as a barrier to stop pathogens e.g. all plants
- bark on trees - forms a protective layer of dead cells e.g. trees
examples of mechanical defences features of plants
- thorns and hairs - deters things from eating them and protects plants from damage e.g. gorse, lamb’s ear
- drooping leaves - stem turns towards ground when touched by an insect making it difficult for them to feed e.g. mimosa
- leaf fall - pathogens that infect leaves fall off the tree in the autumn e.g. deciduous trees
- mimicry - mimic whats around them e.g. passion flower
examples of chemical defences features of plants
- antibacterial chemicals - limits spread of bacteria e.g. mint, witchazel
- poisons - stops them being eaten by herbivores e.g. foxgloves
