Infection & Disease Flashcards
What are pathogens?
Microorganisms that enter your body and cause disease
What are types of pathogens?
Fungi, bacteria, viruses and protists
What type of cells are bacteria?
Prokaryotic, single-celled
What is meant be a cell being Prokaryotic?
It has no nucleus
Can bacteria reproduce rapidly inside the body?
Yes
How does bacteria make you feel ill?
They release toxins that damage your cells and tissues
What do viruses need a host for?
Reproduction and survival
How do viruses work?
They live inside cells and replicate themselves using the cells’ machinery and directing it to make copies of the virus
What happens when a cells has a lot of viruses?
It bursts, releasing all the new viruses
What about viruses make you feel ill?
The damage caused when the cell bursts
What are protists?
Single-celled eukaryotes
What are parasites?
Organisms that live on or inside other organisms and can cause them damage
How are parasites often transferred?
By vectors
Do vectors get the disease itslef?
No
What environment do protists prefer?
Aquatic or moist
How does fungi get food?
By decomposing matter or eating off their hosts
What do some fungi have their body made up of?
Hyphae
What does hyphae do?
Grow and penetrate skin and the surface of plants causing disease
Produce spores to spread to other plants/animals
What are some ways diseases can be spread?
Contaminated water Air (droplet infection) Direct contact Break in the skin Animal vectors Contaminated food
What are some viral diseases?
Measles
HIV
TMV (Tobacco Mosaic Virus)
How is measles spread?
By droplets in the air, from an infected person’s sneeze or cough
What are some symptoms of measles?
Red skin rash
Fever (high temp)
Can measles be serious?
Yes, if there are complications
How is measles prevented?
Most people get vaccinated when they are young
How is HIV spread?
By sexual contact or by exchanging bodily fluids e.g. sharing needles
What are some symptoms of HIV?
Flu-like symptoms for a few weeks
No other symptoms for years
How can HIV be controlled
With antiretroviral drugs - stop it replicating in the body
What does the virus do when you have HIV?
It attacks the immune system
What is the last stage of HIV?
AIDS
What has happened when someone has AIDS?
They can’t defend themselves or cope with other infection or cancers because the immune system is so damaged
What does TMV affect?
Species of plants
What does TMV cause?
A mosaic patter on the leaves of the plant - parts become discoloured
Why does the discolouration of the plant mean?
That the plant can’t carry out photosynthesis as well, affecting it’s growth
What is an example of fungal disease?
Rose Black Spot
What does Rose Black Spot cause?
Purple or black spots to develop on the leaves of rose plants
What can happen to the leaves because of Rose Black Spot?
They can turn yellow and drop off
What does leaves dropping off mean?
That less photosynthesis can take place, meaning the plant doesn’t grow as well
How does Rose Black Spot spread?
Through the environment in water or by the wind
How can Rose Black Spot be treated?
By using fungicides and stripping the plant of affected leaves, which then need to be destroyed so that they can’t spread to other rose plants
What pathogen causes measels?
Virus
What pathogen causes HIV?
Virus
What pathogen causes TMV?
Virus
What pathogen causes Rose Black Spot?
Fungi
What pathogen causes Malaria?
Protist
What pathogen causes Salmonella?
Bacteria
What pathogen causes Gonorrhoea?
Bacteria
What is a disease caused by a protist?
Malaria
What is the vector for Malaria?
Mosquito
How do mosquitos spread Malaria?
They pick up the protist when they feed on an infected animal and every time the mosquito feeds on another animal, it infects it by inserting the protist into the animal’s blood vessels
What does Malaria cause?
Repeating episodes of fever
How can the spread of Malaria be reduced?
By stopping the mosquitos from breeding
How can people protect themselves from mosquitos?
By using insecticides and mosquito nets
What does Salmonella cause?
It causes food poisoning
What are symptoms of Salmonella?
Fever, Stomach cramps, vomiting and diarrhoea
What are symptoms caused by for Salmonella?
Toxins that are produced by bacteria
How can you get Salmonella?
By eating food that has been contaminated with Salmonella bacteria
By eating food that has been contaminated by being prepared in unhygienic conditions
How is the spread of Salmonella controlled?
Most poultry is given a vaccination against salmonella
What is Gonorrhoea?
It’s a sexually transmitted disease
What are symptoms of Gonorrhoea?
Causes pain when urinating
Thick yellow or green discharge from the vagina/penis
How is Gonorrhoea treated?
By an antibiotic called penicillin
What is the problem with Gonorrhoea and penicillin?
Strains of the bacteria are becoming resistent?
How can you prevent Gonorrhoea?
By using barrier methods of contraception e.g. condoms
How can the spread of diseases be reduced?
By being hygienic Destroying vectors Quarantine - isolating infected individuals Vaccination Clean Water + Food Hygiene
How does the skin defend the body?
It acts as a barrier to pathogens
Secretes antimicrobial substances which kill pathogens
How does the hairs and mucus in the nose protect the body?
The mucus traps particles that could contain pathogens
How does the trachea and bronchi protect the body from microbes?
It secretes mucus to trap pathogens
The bronchi is lined with cilia - they waft the mucus up to the back of the throat to be swallowed
What do microbes have on its surface?
Antigens
Antigens are ______ to each _______
Unique
Microbe
Why does the body attack microbes?
Because they recognise it as foreign because of the antigens
What do phagocytes do?
They engulf foreign cells and digest them
What do lymphocytes produce?
Antitoxins and antibodies
What do antibodies do?
They lock onto invading cells so they can be found and recognised by other white cells
They clump the pathogens together so they can easily be engulfed
Antibodies are specific to an _______
Antigen
What happens if someone is infected with the same pathogen again?
The white blood cells rapidly reproduce the antibodies to kill it
What do antitoxins do?
They neutralise toxins produced by invading bacteria
What do memory cells do?
They remember which antibody to produce when infected by a particular pathogen
What is injected in vaccinations?
Dead or weakened (inactive) pathogens that carry antigens
What do white blood cells do when injected with a vaccination?
They produce antibodies for this antigen, even though it is harmless
How do vaccines work?
Inject harmless microbe
Body produces antibodies against antigens
Memory cells remember the antibodies needed to fight this pathogen
If infected with same pathogen, body knows how to fight it - immune
What is meant by immunisation?
The process by which memory cells are made against a pathogen so body’s immune system can quickly destroy it when infected
What is herd immunity?
When enough population are vaccinated that those who can’t be vaccinated due to age/allergies etc. are protected
Differences between primary response (vaccination) and secondary response (infection):
Primary: concentration rises gradually, peaks after a while, less produced, long time
Secondary: concentration rises quickly, more intense response, a lot produced, short amount of time, antibody concentration remains high for a long period of time and take longer to decrease
Pros of vaccines:
Help control communicable diseases that used to be common Big outbreaks (epidemics) can be prevented if a large number vaccinated
Cons of vaccines:
Don’t always work
Someone can have a bad reaction to a vaccine
What are painkillers? What do they do?
They are drugs that relieve pain and the symptoms, but don’t affect the pathogens
What are antibiotics?
They are drugs that kill the bacteria causing the problem without killing any of the body cells
How do antibiotics work?
They interfere with the bacteria’s life cycle - the cell wall (animal cells don’t have them)
Why are there no drugs for viruses?
Because viruses reproduce using the body cells, meaning it’s difficult to develop drugs that only destroy viruses without killing body cells
Why are some bacteria resistant to antibiotics?
because they mutate
How do bacteria become antibiotic resistant?
When infection treated by antibiotics, it will kill the non-resistant strains of bacteria but some of the bacteria that is naturally resistant will survive and reproduce
What is an example of disease that is resistant to antibiotic?
MRSA - resistant to methicillin
3 ways we can slow the rate if development of resistant strains:
- Finish the whole course of antibiotics prescribed
- Only take antibiotics when needed
- Continue developing new antibiotics
What chemicals can be used in drugs?
Chemicals produced by plants to defend themselves against pests and pathogens
What is aspirin?
A painkiller
What is aspirin developed from?
A chemical found in willow
What is digitalis?
A drug that treats heart killers
What is digitalis developed from?
Chemicals found in foxgloves
Who discovered penicillin?
Alexander Flemming
How was penicillin discovered?
An area free of bacteria was seen around a mould on a petri dish containing bacteria. The mould was producing a substance that killed the bacteria
What are new drugs tested for?
Toxicity
Efficiency
Dosage
What happens during the first stage of testing drugs?
Drugs are tested on human cell, tissues and organs in the lab
Why do many drugs fail the first stage of testing?
Because they damage the cells
What happens during the second stage of testing drugs?
Drugs are tested on animals and mammals similar to humans
Why is animal testing continued for a long time?
To make sure the drug is still effective and stays safe - to look for side effects after long-term use
What happens during the third stage of testing drugs?
It is tested on healthy volunteers to make sure it doesn’t have any harmful side effects
How big is the dose given to healthy volunteers during testing?
Low doses at first and gradually increased to see how much is safe to give
What happens after the drug is tested on healthy volunteers?
The drug is tested on people suffering from the illness to see if it works and if it is effectiive
What is the optimum dose?
The dose that is most effective with the least side effects
How is a drug usually tested on patients?
Patients are split into 2 groups - 1 group is given the drug and the other is given a placebo
To see the difference the drug makes
Why are results of drug testing peer reviewed?
To prevent false claims
Why are drugs monitored after being prescribed?
To check their long-term affects
To find contra-indications - what not to have while taking this drug to reduce the danger
What is a placebo?
Something given to the control group, looks like real treatment but has no drug
What is a control group (in testing)?
The group of people that aren’t given the new drug
What is meant by an open trail?
Both the doctor and patient know if the patient is in the control group or not
What is meant by an double blind trail?
Neither the doctor and patient know if the patient is in the control group or not
What is meant by an blind trail?
The doctor knows if the patient is in the control group or not, but the patient does not
What are monoclonal antibodies produced from?
Clones of a single white blood cell - all antibodies are identical and will only target and bind to one specific antigen
How are monoclonal antibodies produced?
A mouse is injected with the antigen and this stimulates mouse lymphocytes to make a particular antibody
How is a hybridoma cell made?
A mouse lymphocyte is fused with a tumour cell
What is the benefit of hybridoma cells?
They divide lots and can be grown very easily
A large amount of _______ can be ________ and ________
Monoclonal antibodies
Antibodies
Collected
Purified
What hormone is found in the urine of pregnant women?
HCG
What are the (4) uses of Monoclonal antibodies?
- Pregnancy tests
- Measure levels of hormones and other chemicals in the blood, or to detect pathogens
- In research, to locate or identify specific molecules in a cell or tissue by binding them to fluorescent dye
- To treat some diseases
How can monoclonal antibodies be used to treat cancer?
Monoclonal antibodies that bind to tumour markers (antigens on cancer cells’ cell membrane) can be made
An anti-cancer drug (a radioactive substance or toxic drug/chemical) can be attached to the antibodies to stop cancer cells growing and dividing
What is the problem of monoclonal antibodies?
It causes more side effects than expected
What happens on the test strip if you are pregnant?
The hormone binds to the antibodies on the the blue beads
The urine moves up the stick, carrying the hormone and beads
The beads and hormones bind to the antibodies on the strip
Blue beads get stuck on test strip, turning it blue
What happens on the test strip if you aren’t pregnant?
The urine moves up the stick carrying the blue beads but there is nothing to stick the blue beads to the test strip, so it doesn’t go blue
Plants need ______ ___. If they don’t have enough they suffer ________ problems
Mineral ions
Deficiency
Why do plants need nitrate?
To make amino acids, that are used in protein synthesis, which is needed for growth
What does a lack of nitrate cause for plants?
Stunted growth
Why do plants need magnesium?
To make chlorophyll, which is needed for photosynthesis
What does a lack of magnesium cause for plants?
Chlorosis - to have yellow leaves
What are common signs of disease for plants?
Stunted growth Patches of decay Malformed stems or leaves Spots on the leaves Abnormal growths Discolouration
What do most plant leaves and stems have as a physical defence from pathogens/insects?
A waxy cuticle
What does a waxy cuticle do?
It acts as a barrier to stop pathogens entering
What are plant cell walls made of?
Cellulose
How does the cell wall protect plants from pathogens/insects?
It acts as a physical barrier against pathogens that make it past the cuticle
How do layers of dead cells around the stems protect plants?
It acts as a barrier to stop pathogens from entering
What chemical defences do plants produce to protect themselves?
Antibacterial chemicals
Poisons
How do antibacterial chemicals protect plants?
They kill bactria
How are poisons effective in protecting plants?
They deter herbivores
How do thorns and hairs protect plants?
They stop animals from touching and eating the plants
How do leaves curling or drooping when touched protect plants?
It prevents them from being eaten by knocking insects off them and moving away from things
