Infection and Response Flashcards
What do pathogens release which cause you to feel unwell ?
Toxins
How does a bacterial infection cause you to feel unwell ?
- Bacteria divide rapidly
- Release toxins which cause you to feel unwell
How does a virus cause you to feel ill ?
- viruses invade your cells and divide rapidly
- causes damage to the cells ( cells burst which causes them to die)
How is the chicken pox virus spread and what are the symptoms ?
- spread by direct contact
Transferred if you touch the pus that comes from the spots, caused by chicken pox
Symptoms: rash, coughing, sneezing
How is Malaria spread and what are the symptoms ?
- Spread by vectors specifically mosquitos
Mosquito takes blood and microorganism ( that causes malaria from infected person
When mosquito bites another person, microorganism is transferred and they catch malaria
Symptoms: Head ache. vomiting, diarrhoea
How is a common cold spread and what are the symptoms ?
- Spread by air droplets
If someone inhales the air droplets they become infected with the virus
Symptoms: coughing, sneezing, sore throat, headache
How is food poisoning spread and what are the symptoms ?
- Spread by contaminated food (caused by bacteria in food)
Symptoms: vomiting, diarrhoea and muscle cramps
How is rabies spread and what are the symptoms ?
- spread by animals
If an animal infected with rabies bites you, virus enters your body through the cut when you’re bitten
Symptoms: Flu like symptoms, hallucinations, brain damage/ death
How is tetanus spread and what are the symptoms ?
- Transmitted if you have an open cut that touches something with the tetanus bacteria on it
or if something with the tetanus bacteria on it pierces your skin
Caused by a bacteria which lives in dirty objects ie rusty nails
Symptoms: lockjaw, spasms
How is cholera spread and what are the symptoms ?
- transmitted in dirty water or contaminated food ( caused by a bacteria)
for example if someone infected with cholera goes to the toilet in the river and then someone else drinks from the river, they may become ill
Symptoms: vomiting, diarrhoea and muscle cramps
How is HIV spread and what are the symptoms ?
Spread by sexual contact ( bodily fluids ie blood, semen, vaginal fluids, breast milk)
Symptoms: fever, chills, fatigue, muscle ache, swollen lympth nodes
What does HIV stand for ?
Human immunodeficiency virus
How does the HIV virus work ?
- virus enters the body
- HIV tricks the T- cell receptors to not recognise the virus, so it can invade the cell
- Enters the cell and releases 2 viral RNA strands and 3 essential replication enzymes
- RNA strands transcribed into DNA and the DNA is integrated into the genome of the host cell
- causes host cell to make more copies of the HIV, which leave host cell to seek more T-Cells to damage
What type of cells does HIV specifically target ?
T- helper cells, a type of white blood cell
What are antiretroviral drugs ?
Slow virus down by blocking certain enzymes that are needed for virus to multiply
Are viruses alive ?
Half alive and half not alive
Don’t do anything on their own, including reproducing, until they come into contact with a suitable animal or plant cell
How big are viruses ?
They are the smallest type of microbe, smaller than bacteria
Do viruses have a nucleus ?
No, genetic information “floats” around inside of them
Can viruses move ?
No, they are carried by the blood stream
What is a mutation ?
A change in the virus’ genome
Why is it neccessary to vaccinate poultry ?
- To stop humans eating contaminated chicken
- to provide herd immunity
How does Malaria spread ( detailed explanation) ?
Infected mosquito bites human skin
Parasite plasmodium ( protist that causes malaria) goes to the liver
parasite can enter liver cells, reproduce and copies burst out of liver cells
Get into the bloodstream and continue reproducing
Infected red blood cells burst, infecting other blood cells
Removes capacity for carrying oxygen and causes fever and chills
Dormant version of malaria travels through host’s blood stream, waiting to be ingested by another mosquito to carry it to a new host
What is the tobacco mosaic virus ?
Widespread plant pathogen that affects approx 150 species of plant ie tobacco plant and tomato plant
How is the tobacco mosaic virus spread ?
Spread by direct contact between diseased plant and healthy plant
Spread also by vectors ie insects
How can the TMV virus be avoided ?
good field hygiene and pest control
growing TMV resistant strains of crops
What are the symptoms of TMV virus ?
- mosaic pattern of discoloration on leaves
- malformation of leaves or growing points
- yellow spotting on leaves
How is measles virus spread and what are the symptoms ?
Spread by air droplets ie from coughs and sneezes
Symptoms: fever, red skin rash
What does the MMR vaccine prevent ?
Measles, mumps and rubella
What can be used to treat bacteria and not viruses ?
Antibiotics
How is the bacteria that causes salmonella spread ?
By ingesting contaminated food
What are the symptoms of salmonella ?
Same as the symptoms of food poisoning
vomiting, diarrhoea and muscle cramps
How is gonorrhoea transmitted ?
Transmitted through sexual contact ie intercourse
How can the spread of gonorrhoea be stopped ?
using a condom during intercourse
people who have unprotected sex should be tested for it so they can be treated to kill bacteria before they pass it on
What are the symptoms of gonorrhoea ?
thick yellow/ green discharge from penis/ vagina
pain when urinating
How can a person with a mild salmonella infection prevent the spread of the bacteria to others ?
- don’t prepare food while infected
- disinfect clothes/ surfaces
- do not share utensils/ cutlery/towels
Why would a person with AIDS take longer than a healthy person to recover from a salmonella infection ?
- immune system is damaged/ weakened
- white blood cells cannot kill bacteria as effectively
What is athlete’s foot caused by and how is it spread ?
Caused by a fungus
Spreads through contact with an infected person or from contact with contaminated surfaces ie public showers
How can spread of athlete’s foot be prevented ?
- keeping your feet clean and dry
- not sharing towels, socks and shoes
- not walking barefoot in public areas
How does athlete’ s foot affect your skin ( symptoms) ?
Skin may become itchy, red, scaly, cracked or blistered
How does athlete’s foot affect the growth of an organism
fungi called dermatophytes feed off dead skin and keratin and multiply, causing damage to the organism’s cells.
What is keratin and what does it help form ?
A type of protein found on epithelial cells, which line the inside and outside surfaces of the body.
Helps form tissues of the hair, nails, and the outer layer of the skin.
What is rose black spot caused by and how is it spread ?
Caused by a fungus
Spread through air and water in soil
How can spread of rose black spot be prevented ?
By removing affected leaves and using fungicides
What are the symptoms of rose black spot ?
purple or black spots
leaves turn yellow and drop early
How does rose black spot affect the growth of an organism ?
Reduces photosynthesis if the number of leaves of the plant decreases
How can the spread of Malaria be prevented ?
By preventing mosquitos from breeding ( removing stagnant water), mosquito nets, using repellants to avoid being bitten, antimalarial medications
How does the skin defend our body against pathogens ?
- Acts as a protective barrier to stop pathogens from entering
- Skin produces antimicrobial secretions to destroy pathogenic bacteria
- healthy skin is covered with microorganisms that act as an extra barrier to entry of pathogens
How does your nose defend against pathogens ?
- Nose is full of hairs and produces mucus
- hairs and mucus trap particles form the air that may contain pathogens or irritate lungs
How do the trachea and bronchi defend against pathogens ?
- Trachea and bronchi secrete mucus that traps pathogens from the air
- cilia wafts mucus out of the lungs ( cilia found on lining of trachea and bronchi )
How does the stomach defend against pathogens ?
Stomach produces stomach acid that destroys
microbes in the mucus you swallow and microbes in
food and drink
What are antibodies and what do they do ?
A protein released by white blood cells that attaches to the surface of a pathogen
They inactivate or destroy pathogens
What do antitoxins do ?
counteract the toxins produced by pathogens
What are the two types of white blood cells ?
Phagocytes and lymphocytes
What are antigens ?
Unique proteins on the surface of all our body cells which act as a signature so your body can identify you
What are memory cells ?
Long lived immune cells capable of recognising foreign particles they were previously exposed too
Why are memory cells useful ?
- the right antibody is made faster next time
- we won’t feel unwell if same pathogen reenters our body
What does herd immunity mean ?
If the majority of a community are protected, then the disease can’t spread
What is the difference between the first and second time your body is exposed to the same pathogen ?
- first exposure, there is a lag time of 7 days before body starts to produce antibodies
( when body starts to produce antibodies there is an immune response)
- second time body is exposed to the same pathogens, body produces antibodies straight away in a much larger quantity
What are the symptoms of immune response ?
Coughing, sneezing, runny nose, fever
How does a vaccine work ?
- a weakened or dead form of the pathogen is inserted in the person’s body by injection
- immune system recognises foreign antigens
- causes lymphocytes to make antibodies specific to the pathogen
- antibodies latch onto the antigens on the surface of the pathogen and inactivate it
- phagocytes engulf pathogens
- memory cells remember the pathogen and respond quickly when in reenters body
Where does the heart drug digitalis originate from ?
foxgloves
Where does aspirin originate from ?
willow trees
What does medicine do ?
- relieves symptoms of disease
- kill the pathogens
What do bacteria need in order to grow ?
Nutrients, warmth and oxygen ( for respiration )
What is the method for culturing bacteria using agar jelly ?
Step 1: Sterilise petri dishes, bacterial nutrient broth and agar to kill unwanted microorganisms and prevent contamination
Step 2: Sterilise innoculating loop by passing it through a flame and then use it to transfer bacteria onto the petri dish
Step 3: Attach the lid using adhesive tape to stop it from falling off and unwanted microorganisms entering
Step 4: Place agar plate upside down into an incubator. Stops moisture dripping down on bacteria and disrupting colonies
In school laboratories what temperature is bacteria normally incubated at ? why ?
25 degrees celsius
To prevent chances of harmful bacteria growing
How to find the effect of antibiotics on bacterial growth ?
Step 1: clean working bench with disinfectant solution to kill microorganisms that could contaminate bacteria cultures
Step 2: Sterilise an innoculating loop by passing it through a flame
Step 3: Open a sterile agar gel plate near a bunsen burner flame. Flame kills bacteria in air
Step 4: Use loop to transfer bacteria onto plate
Step 5:Place sterile filter paper discs containing antibiotics onto plate
Step 6: Incubate plate at 25 degrees celsius
What is the zone of inhibition ?
The region around the antibiotic discs where the bacteria hasn’t grown
How can we measure the effect of the antibiotic ?
Calculating area of zone of inhibition
area = pi x radius ( squared)
What are the qualities of good medicine ?
Effectiveness - able to cure/ improve health
Safety - not too toxic or having unacceptable side effects
Stability - used under normal circumstances and can be stored
Successfully removed - Able to be removed after its job is done
How does a good double blind trial work ?
- patients split into groups by a random number generator. Each group has a doctor
- One group gets a fake drug called a placebo and the other group gets the real drug
- results published in medical journals and data is critically evaluated by scientists to stop false claims
What does it mean by a double blind trial ?
Both the doctor and patients don’t know who has the placebo and who has the real drug
What are the stages of clinical trials ?
Pre- clinical trial stage 0 : establishing dosage of the drug, how much you give, how often you give medicine
Stage 1: Drug is first tested on young men, not young women in case they are pregnant
Stage 2: Drug tested on patients who are very ill, experimentation with different doses of drug
- needs lots of money and only best universities take part
Stage 3: Drug tested on thousands of patients
Must have a standardised testing regime (a protocol)
Stage 4: Follow up studies to find new uses in new patient groups, and new combinations and doses. Study report is put together and submitted to regulatory authority for approval. Other scientists peer review the journals on drug research.
Why are clinical trials used ?
To establish if drug is safe and effective
How long can the journey of drug development take ?
Up to 8 or even 10 years
Why do the final results of clinical trials have to be peer reviewed before they are published ?
To prevent false claims
