infection and response Flashcards
what is a communicable disease
a disease caused by a pathogen which can be passed between animals or plants
what is a pathogen
a disease-causing microorganisms
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
they invade and reproduce inside living body cells, leading to cell damage
give 3 ways pathogens can be spread
air
water
direct contact: common in plant diseases and sexually transmitted infections
4 ways the spread of pathogens can be reduced
hygiene
reducing contact
removing vectors
vaccination
why is it especially important to prevent the spread of viral diseases
scientists have not yet developed cures for diseases
what is measles
measles is a serious viral disease that can cause blindness and brain damage. the main system are a fever and a red skin rash
how is measles spread
by air
through inhalation of droplets from coughs and sneezes
what is HIV
HIV is a virus which attacks and damages the immune system until it can longer function properly,
what is aids
aids is the condition resulting from a long-term HIV infection
how is HIV spread
direct sexual contact
exchange of bodily fluids
how can the spread of HIV be prevented
use of condoms
screening for blood transfusions
not sharing needles
bottle-feeding by HIV positive mothers
use of drugs
what is tobacco mosaic virus
a plant pathogen which causes leaf discolouration when cells are damaged. affected areas cannot photosynthesise, reducing crop yield. as there is no treatment, farmers grow TMV-resistance crop strains to avoid infection
how is tobacco mosaic virus spread
contact between infected and healthy plants
insects may act as vectors which transfer the virus between different plants
what is salmonella
a type of bacteria found in raw meat, poultry and eggs
if they enter the body via food poising - they can affect natural gut bacteria
symptoms of salmonellae
fever
abdominal cramping
vomiting
diarrhoea
possibly could be fatal
how can the spread of salmonella be limited
vaccinating animals intended for consumption
keep raw meat away from cooked meat
disinfect hands and surfaces
thoroughly cook meat
what is gonorrhoea
a sexually transmitted bacterial infection cause by unprotected sex with an infected individual
early symptoms include yellow and green discharge from genitals and painful urination although it may be symptomless
how is gonorrhoea controlled
its spread can be controlled through the use of antibiotics and using condoms
what is rose black spot
a fungal disease which causes purple or black spots to develop on rose leaves
reduces the area of the leaf which is available for photosynthesis and causes leaves to turn yellow and drop prematurely
how is the rose black spot fungus spread
fungal spores are spread by the wind and in water
how can the rose black spot fungus be treated
using fungicides
destroying infected leaves
what is malaria
malaria is a disease caused by protist pathogens
the disease is carried from host to host by mosquitoes, and the protists enter the human blood stream when they feed. symptoms include fever and shaking and it may also be fatal in some cases
how can the spread of malaria be reduced
using insecticides
using insect nets to avoid bites
prevent mosquito breeding by removing segment water
antimalaria drugs
how does the skin prevent pathogens from entering the body
acts as a physical barrier
scab formation after skin is cut or wounded
antimicrobial secretions which can kill pathogens
healthy skin flora complete with pathogens and act as an additional barrier
how does the respiratory system prevent pathogens from entering the body
nose: has hair and mucus which traps pathogens
trachea and bronchi: have mucus and traps pathogen. ciliated cells move mucus to the mouth so it can be swallowed
how does the stomach prevent pathogens infecting the body
secretes hydrochloric acid
kills any pathogens present
how does phagocytosis protect us against disease
white blood cells ingest and destroy pathogens so they cannot infect more cells
how does antibody production protect us against the disease
white blood cells produce antibodies which are complementary to specific antigen on a pathogen. the binding of antibodies to antigens causes pathogens to clump together, making them easier to destroy.
how does antoxtin production protect us against disease?
antitoxins bind to toxins released by pathogens and neutralise them
what is a vaccination?
contains a dead or inactivated form of the pathogen which stimulates white blood cells to produce complementary antibodies to the pathogen. in the case of second infection, memory cells can rapidly produce the correct antibodies and prevent illnesses
what is herd immunity
if a sufficiently high proportion of the population are immune to a disease, the spread of the disease will be limited.
advantages of vaccinations
they have eradicated many deadly diseases
many epidemics can be prevented by vaccinations
herd immunity protects those who cannot have vaccinations
disadvantages of vaccinations
not always guaranteed to work as they may not work against multiple strains of a pathogen
may have side effects
what drugs are used to cure some bacterial diseases
antibiotics
kill pathogens inside the body
how do antibiotics work
antibiotics kill bacterial pathogens inside the body but do not kill human cells
some antibiotics kill a wide range of bacteria, it is important that the right antibiotic is used for a specific bacteria
why can antibiotics not be used to treat viral diseases
antibiotics have no effect on viral pathogens as they live inside the host’s cells
therefore it is difficult to design drugs that would kill the virus and not destroy human cells at the same time
what is antibiotic resistance
antibiotic resistance occurs when mutations lead to individual bacteria being resistant to an antibiotic
these bacteria are able to survive, reproduce and pass on their genes, leading to more antibiotic resistant bacteria
this is concerning as some types of bacteria are becoming resistant to all known antibiotics, so the diseases they use cannot be cured
how can we prevent antibiotic resistant
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 only treat the symptoms they do not kill pathogens
what plant is the heart drug digitalis extracted from
foxgloves
what painkiller originates from a compound found in willow bark
aspirin
what antibiotic was discovered by Alexander Fleming from a type of mould
penicillin
4 qualities of good medicine
effective
safe
stable
able to be taken in and removed easily
3 main drug factors used for testing and developing new drugs
toxicity
efficiency
dosage
how is preclinical testing carried out
labs
uses cells, tissues, and live animals
how is clinical testing carried out
uses healthy volunteers and patients
firstly the drug is tested at a low dose on healthy people, then tested on patients and on a larger scale to find the optimum dose. often one group will be given a placebo and the other group given the real drug to discover the efficiency
difference between single-blind and double-blind trial
in a single-blind trial, only the doctor knows whether the patient receiving the drug or placebo.
in a double blind trial, neither the patient nor the doctor knows
advantage of double blind trial
removes bias on the part of the doctor
what is peer review
where the results of the drug trials are checked over by other scientists knowledgeable in this field
what are monoclonal antibodies
antibodies that are clones from one parent cell
specific to one type of antigen
describe how monoclonal antibodies are produced
- specific pathogen injected into animal (mouse)
- B-lymphocytes producing complementary antibodies to be extracted
- b-lymphocytes fuse with tumour cells to form hybridoma cells, they cells can divide quickly and produce an antibody
- hydridoma cells cultured
- monoclonal antibodies collected and purified
uses of monoclonal antibodies
detection of pathogens
location of cancer cells and blood clots
treatment of cancer
used in pregnancy testing kits
what do pregnancy kits test for
hCG in urine
what does a pregnancy test consist of
a stick containing monoclonal antibodies specific to hCG
- monoclonal antibodies attached to a blue bead which are free to move
- monoclonal antibodies attached to the test stick
describe what happens to the test stick if a women is pregnant
- hCG in urine binds to monoclonal antibodies attached to a blue bead
- monoclonal antibodies with hCG diffuse up dipstick
- monoclonal antibodies fixed to the stick bind to hCG
- blue line forms
describe what happens to the test stick of the pathogen is not present
no hCG in urine so a blue line is not formed
advantage of using monoclonal antibodies to test for pathogens
specific to one antigen
very accurate
quick results
why can monoclonal antibodies be used to target cancer cells
cancer cells have specific antigens caller tumour markers on their membranes
monoclonal antibodies are specific to one type of antigen so can be targeted to tumour markers without damaging other cells
describe how monoclonal antibodies can be used to diagnose cancer
- monoclonal antibodies tagged to radioactive substance
- monoclonal antibodies injected into patients blood stream
- monoclonal antibodies bind to tumour markers on cancer cells
- emitting 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
- monoclonal antibodies attached to an anti-cancer drug
- monoclonal antibodies injected into patients bloodstream
- monoclonal antibodies bind to tumour markers on cancer cells
- anti cancer drug destroys cancer cells
why are cancer treatments that use monoclonal antibodies favoured over traditional treatments
radiotherapy and chemotherapy target rapidly dividing cells, health cells are damaged as a consequence producing unpleasant side effects
whereas
monoclonal antibodies target only cancer cells reducing damage to normal cells
how can monoclonal antibodies be used to locate blood clots
monoclonal antibodies tagged to radioactive substance
monoclonal antibodies bind to specific protein in blood clots
radiation emitted by monoclonal antibodies is detected, enabling the location of blood clots to be found
how do aphids cause damage to plants
they use their sharp mouth parts to extract sap from the plant phloem, weakening the plant
they are also vectors who can transfer pathogens from diseases plants to healthy plants
how to reduce no. of aphids
chemical pesticides
biological pest control (ladybirds)
why do plants need a good supply of nitrate ions
nitrate ions are required to convert sugars into proteins which are required for the plant to grow. as a result, the growth of the plant will be stunted if there is not an adequate supply of nitrates
why do plants need a good supply of magnesium ions
magnesium ions are required to synthesis chlorophyll, which absorbs light energy during photosynthesis. as a result, the leaves cannot photosynthesis properly and then turn yellow
symptoms of disease in plants
stunted growth
spotted leaves
decay and rotting
growths
malformation of stems and leaves
discolouration
presence of pests
3 ways in which plant disease can be identified
reference to gardening websites or manuals
lab testing
monoclonal antibody test kits
give examples of physical defence responses used by plants
cellulose cell walls
tough waxy outer layer
outside layer on stems
leaf fall
give examples of chemical defences used by plants
antibacterial chemicals
poisons
give examples of mechanical defences used by plants
thorns and hairs to deter animals
leaves that drop and curl on contact
mimicry to trick animals
