Topic 3-Infection And Response Flashcards Preview

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Flashcards in Topic 3-Infection And Response Deck (95):


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



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

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



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



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



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



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



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

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

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


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

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

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