Topic 3-Infection And Response Flashcards
Pathogens
Pathogens are microorganisms that enter the body and cause disease
Pathogens cause communicable disease-what is a communicable disease
Diseases that can be easily spread
What can be infected by pathogens
Both plants and animals
What are the four types of pathogen
Bacteria
Viruses
Protists
Fungi
What are bacteria
Very small cells which can reproduce rapidly in your body
What can bacteria do
They can make you feel ill by producing toxins that damage your cells and tissues
What are viruses
They are not cells but they are tiny. They also can reproduce rapidly inside the body
How to viruses work
They live inside your cells and replicate themselves. The cell will then burst, releasing all the new viruses. This cell damage is what makes you feel ill
What are protists
They are single-celled eukaryotes
How do protists work
Some protists are parasites. Parasites live on or inside other organisms and can cause them damage. They are often transferred to the organism by a vector, which doesn’t get the disease itself (eg an insect)
What are fungi
Some fungi are single celled. Others have a body which is made up of hyphae
What do hyphae do
These hyphae grow and penetrate human skin and the surface of plants, causing diseases. The hyphae can produce spores, which can be spread to other plants and animals
What are the ways pathogens can be spread
Water
Air
Direct contact
How are pathogens spread through water
Some pathogens can be picked up from drinking or bathing in dirty water.
How can pathogens be spread by air
Pathogens can be carried in the air and breathed in. Some airborne pathogens are carried in the air in droplets produced when you sneeze or cough
How can pathogens be spread by direct contact
Some pathogens can be picked up by touching contaminated surfaces, including skin
Is measles a viral, fungal, bacterial or protist disease
Viral
How is measles spread
It is spread by droplets from an infected person’s sneeze or cough
What does measles do
People with measles develop a red skin rash, and they show signs of a fever. Measles can be very serious if there are complications. For example it can sometimes lead to pneumonia.
Most people are vaccinated against measles when they are young
Is HIV a viral, fungal, bacterial or protist disease
Viral
How is HIV spread
It is spread by sexual contact or by exchanging bodily fluids such as blood eg by sharing needles
What does HIV do
Initially it can cause flu like symptoms for the first few weeks.
How can HIV be controlled
By using antiretroviral drugs which stop the virus replicating in the body.
How does HIV work
It attacks the immune cells
What is AIDS
If the body’s immune system is badly damaged, it can’t cope with other infections or cancers.
What is tobacco mosaic virus
It is a virus that affects many species of plants
What does tobacco mosaic virus do
It causes a mosaic pattern on the leaves of plants and parts of the leaves become discoloured. The discolouration means the plant can’t carry out photosynthesis as well so the virus affects growth
Is rose black spot a viral, fungal, bacterial or protist disease
Fungal
What is rose black spot
It is a fungus that causes purple or black spots to develop on the leaves of rose plants. The leaves can then turn yellow and drop off. This means that less photosynthesis can happen so the plant doesn’t grow very well
How is rose black spot spread
It spreads through the environment in water or by wind
How can rose black spot be treated
Gardners can treat the disease using fungicides and by stripping the plant of its affected leaves. These leaves then need to be destroyed so that the fungus can’r spread to other rose plants
Is malaria a viral, fungal, bacterial or protist disease
Is is caused by a protist
Where does part of the mararial protists life cycle happen
Inside a mosquito
What are mosquitoes
They are vectors-they pick up the malarial protist when they feed on an infected animal
How is malaria spread
Everytime the mosquito feeds on another animal it infects it by inserting the protist into the animal’s blood vessels
What does malaria do
It causes repeating episodes of fever and can be fatal
Is salmonella a viral, bacterial, fungal or protist disease
Bacterial
What is salmonella
It is a type of bacteria that causes food posioning
What does salmonella do
Infected people can suffer from fever, stomach cramps, vomiting and diarrhoea
How is salmonella spread
The symptoms are caused by the toxins that the bacteria produce. You can get salmonella by eating food that has been contaminated with salmonella bacteria
Is gonorrhoea a viral, fungal, bacterial or protist disease
Bacterial
What is gonorrhoea
It is a sexually transmitted disease which is passed on by sexual contact
What does gonorrhoea do
A person with gonorrhoea will get pain when they urinate. Another symptom is thick yellow or green discharge
How was gonorrhoea originally treated
It was originally treated by the antibiotic penicillin but now this is more difficult because strains of bacteria have become resistant to it
How can gonorrhoea by prevented
People can be treated with antibiotics and should use barrier methods of contraception
How can the spread of disease be reduced
-Being hygenic
Doing things like washing your hands before preparing food or after you’ve sneezed
How can the spread of disease be reduced
-Destroying vectors
Vectors can be killed by using insecticides or by destroying their habitat so they can no longer breed
How can the spread of disease be reduced
-Isolating infected individuals
If you isolate someone who has a communicable disease this prevents them from passing it on to anyone else
How can the spread of disease be reduced
-Vaccination
Having a vaccination means that they can’t develop the infection and then pass it on to someone else
How does the body stop pathogens getting in
-Skin
The skin acts as a barrier to pathogens. It also secretes antimicrobial substances which kill pathogens
How does the body stop pathogens getting in
-Hairs and mucus
Hairs and mucus in the nose trap particles that could contain pathogens
How does the body stop pathogens getting in
-Trachea and bronchi
The trachea and bronchi secrete mucus to trap pathogens. Also they are lined with cilia, these are hair-like structures which waft the mucus up to the back of the throat where it can be swallowed
How does the body stop pathogens getting in
-The stomach
The stomach produces hydrochloric acid. This kills pathogens that make it that far from the mouth
What happens if pathogens do make it into your body
The immune sytems tries to get rid of them
How the immune system destroys pathogens
-Consuming them
White blood cells can engulf foreign cells and digest them. This is called phagocytosis
How the immune system destroys pathogens
-Producing antibodies
Every pathogens has antigens on its surface. Some white blood cells will produce antibodies when they come across a foreign antigen. This locks onto the invading cells so they can be found and destroyed by other white blood cells. Antibodies are produced rapidly and carried around the body. If the person if infected again they already have the right antibodies so are naturally immune
How the immune system destroys pathogens
-Producing antitoxins
These counteract toxins produced by the invading bacteria.
What do vaccinations involve
Injecting small amounts of dead or inactive pathogens. These carry antigens which cause your body to produce antibodies to attack them even though the pathogen is harmless. So if live pathogens of the same type enter the body the body already has the correct antibodies so can kill the pathogen
What is the MMR vaccine
It contains weakened versions of the viruses that contain measles, mumps and rubella
Pros of vaccination
They have helped control communicable diseases that were once common in the uk. Big outbreaks (epidemics) can be prevented if a large number of the population are vaccinated.
Cons of vaccination
Vaccines don’t always work.
You can sometimes have a bad reaction to a vaccine, but bad reactions are very rare
What do painkillers do
They are drugs that relieve pain. However, they don’t actually tackle the cause of the disease or kill pathogens, they just help relieve symptoms.
What do antibiotics do
They actually kill or prevent the growth of the bacteria causing the problem without killing your own body cells. Different antibiotics kill different types of bacteria so you have to be treated with the right one
Con os antibiotics
They don’t destroy viruses. Viruses reproduce using your own body cells which makes it very difficult to develop drugs that destroy just the virus without killing the body’s cells
Bacteria can become resistant to antibiotics
Bacteria can mutate to become resistant. This means if you treat the infection, only non-resistant strains will be killed. The resistant bacteria will reproduce so the population of the resistant strain will increase. To slow down the development of resistant strains doctors shouldn’t over prescribe antibiotics
Making drugs from plants
Plants produce a variety of chemicals to defend themselves against pests and pathogens. Some of these chemicals can be used as drugs to treat human diseases or relieve symptoms. A lot of our current medicines were discoverer by studying plants used in traditional cures
Drug testing
•Stage 1 (preclinical)
Drugs are tested on human cells and tissues in the lab. However you can’t use human cells and tissues to test drugs that affect whole or multiple body systems
Drug testing
•Stage 2 (preclinical)
Testing the drug on live animals. This is to test efficacy (wether it works and produces the right effect), its toxicity and to find the best dosage
Drug testing
•Stage 3 (clinical)
If it passes the animal test then it is tested on human volunteers. First on healthy volunteers to test for side effects. Then on sufferers to find an optimum dosage. Then some people take the drug and some take a placebo to see the effects. The patient or doctor doesn’t know wether they have a placebo or not. Results then have to be peer reviewed
What are antibodies produced by
B-lymphocytes (a type of white blood cell)
What are monoclonal antibodies
Identical antibodies
How are monoclonal antibodies produces
From lots of clones of a single white blood cell. This means they are identical and target one specific protein antigen
What is a hybridoma
Lymphocytes don’t divide very easily but tumour cells can be grown very easily. A hybridoma is a B-lymphocyte fused with a tumour cell.
What are hybridomas useful for
They can be cloned to get lots of identical cells. These cells produce the same antibodies. These antibodies can be collected and purified
Why are monoclonal antibodies useful
You can make monoclonal antibodies that bind to anything. Monoclonal antibodies are useful because they will only bind to this molecule which means you can use them to targer a specific cell or chemical in the body
How pregnancy tests work
The part of the test you urinate on has antibodies to the hormone of pregnant women, with blue beads attached. The test strip (the bit that turns blue) has some more antibodies of the hormone on
How pregnancy tests work
-If you are pregnant
The hormone binds to the antibodies on the blue beads. The urine moves up the stick, carrying the hormone and the beads. The beads and hormone bind to the antibodies on the strip. So the blue beads get stuck on the strip, turning it blue
How pregnancy tests work
-If you’re not pregnant
The urine still moves up the stick, carrying the blue beads but there’s nothing to stick the blue beads onto the test strip so it doesn’t go blue
Monoclonal antibodies can be used to treat diseases
Cancer cells have antigens on their cell membranes. You can make monoclonal antibodies to bind to these. An anti-cancer drug can be attatched to these antibodies. The antibodies are given to a patient through a drip. Antibodies only target the cancer cells. The drug kills cancer cells but not any normal cells
Monoclonal antibodies can also be used to
Bind to hormones and other chemicals in the blood to measure the levels.
Test blood samples in labs for certain pathogens.
Locate specific molecules on a cell or in a tissue
How monoclonal antibodies are used to locate specific molecules on a cell or tissue
First monoclonal antibodies are made that will bind to the specific molecules. The antibodies are bound to flourescent dye. If the molecules are present in the sample, the monoclonal antibodies will attach to them and can be detected using the dye
Problems of monoclonal antibodies
Monoclonal antibodies cause more side effects than originally expected. This means they are not as widely used as scientists originally thought they would be
Plants need mineral ions
Plants need mineral ions from the soil, if they don’t have enough they suffer deficiency symptoms
Plants need nitrates for
Nitrates are needed to make proteins and therefore for growth.
A lack of nitrates causes stunted growth
Plants need magnesium for
Magnesium ions are needed for making chlorophyll, which is needed for photosynthesis. Plants without enough magnesium suffer from chlorosis and have yellow leaves
The common signs that a plant has a disease
- Stunted growth
- Spots on leaves
- Patches of decay
- Abnormal growths
- Malformed stems or leaves
- Discolouration
How to identify plant diseases
Look up the signs on a gardening website. Take the infected plant to a lab where scientists can identify the pathogen. Using testing kits to identify the pathogen using monoclonal antibodies
Plants physical defences
•Waxy cuticle
Most plant leaves and stems have a waxy cuticle which provides a barrier to stop pathogens entering
Plants physical defences
•Cell walls
Plant cells are surrounded by cell walls made from cellulose. These form a physical barrier against pathogens that make it past the waxy cuticle
Plants physical defences
•Layers of dead cells
Plants have a layer of dead cells around their stems, eg the outer part of the bark on a tree.
These act as a barrier to stop pathogens entering
Plants chemical defences
•Antibacterial chemicals
Some plants can produce antibacterial chemicals which kill bacteria
Plants chemical defences
•Poisons
Other plants produce poisons which can deter herbivores
Plants mechanical defences
•Thorns and hairs
Some plants have adapted to have thorns and hairs which stop animals from touching and eating them
Plants mechanical defences
•Droop or curl leaves
Other plants have leaves that droop or curl when touched. This means they can prevent themselves from being eaten by knocking insects off and moving away from things
Plants mechanical defences
•Mimicking
Some plants can mimic other organisms
EG: Some plants in the ice plant family in Southern Africa look like stones and pebbles which tricks other organisms into not eating them
