B2 Flashcards
What is a pathogen?
A microorganism that causes disease
Name 4 different types of pathogens
Protists, Fungi, Bacteria, Viruses
What are bacteria?
They are prokaryotic, very small cells that reproduce rapidly, and produce toxins that damage your cells and tissues
What are protists?
They are eukaryotic, single-celled organisms that vary in size
What are fungi?
Some are single-celled, some are bodies. They grow and penetrate human skin/surface of plants causing diseases. They also produce spores which can spread to other organisms
What are viruses?
They are not cells. They are INCREDIBLY small, and replicate themselves inside the infected organism’s cells, causing them to burst and release more viruses
Describe 2 ways white blood cells protect your body from pathogens
Consuming them- phagocytes have a flexible membrane and lots of enzymes. This allows them to engulf and digest the pathogen.
Producing antibodies- white blood cells that detect foreign antigens can create antibodies that lock onto and disable the pathogen, making it easier for the phagocyte to engulf them
What is a memory cell?
White blood cells that stay around in the blood after a pathogen has been fought off. If the same pathogen returns, the memory cells will trigger the rapid production of the same antibodies needed to destroy it, meaning you will not get the disease
Summarize the process of making monoclonal antibodies
An animal is injected with the antigen you want to target. The animal then produces antibodies to counteract the antigen. A blood sample is then taken from the animal and the correct antibody is extracted. The antibody is fused with tumour cells (which can divide many times) and is then cloned many times in a lab
What is an incubation period?
The time from the moment of infection until signs and symptoms of the disease appear
What are 3 common causes of disease / ill health?
1) Pathogen infection
2) Genetic mutation
3) Environmental factors
What are non-communicable diseases?
Diseases that cannot be passed from one organism to another- they are associated with genetic mutations and environmental factor and they generally last for a long time and progress slowly`
What are communicable diseases?
Diseases that can be passed from one organism to another- they are caused by a pathogen infecting the organism
What are the 7 ways communicable diseases can be spread?
1) Water
2) Air
3) On surfaces
4) Body fluids
5) Animal vectors
6) Soil
7) Food
State 1 human physical defence and how it defends you
The skin is a barrier protecting vulnerable areas from pathogens
State 1 human chemical defence and how it defends you
Saliva contains molecules that kill pathogens that enter the mouth
State 1 human microbial defence and how it defends you
Natural bacteria in the gut will compete with pathogens for necessary survival resources, making it harder for pathogens to survive
State 1 plant physical defence and how it defends the plant
Plant cell walls are a barriers preventing pathogens from entering
Why is preventing pathogens from attacking plants important?
Plants are at the start of most food chains, therefore if many plants are taken out by pathogens, then it will have a negative knock on effect for the rest of the food chain
State 1 feature of a plants immune system
If pathogens manage to bypass the plants physical defences, then the plant can produce antimicrobial substances as a chemical defence
State 3 ways the spread of disease in humans can be reduced
1) Sterilise wounds
2) Live in sanitary conditions
3) Vaccinations
State 3 ways the spread of disease in plants can be reduced
1) Destroy infected plants
2) Crop rotation
3) Polyculture
What is crop rotation and what are the pros and cons?
Crop rotation is the regular change of type of plant, in the aim to prevent pathogens from being established. However this makes farming less profitable, as it has to change farming practices often
What is polyculture and why is it useful in preventing the spread of disease?
Polyculture is growing different types of plants in a single area at the same time- this is useful as if a pathogen specific to a certain plant, it is less likely to infect neighboring crops as it is surrounded by different types
How do vaccinations work?
In vaccinations, you are injected with a dead, inactive or weakened pathogen, and even though they are harmless, they will trigger an immune response and create antibodies to attack the pathogens.
After the vaccinations, some of the white blood cells with remain in the blood as memory cells, so if the same type of pathogen reappears at any point, there will be antibodies ready to attack instantly
Why are vaccinations important?
They rid of the period of being injected with a new pathogen and the white blood cells making the correct antibodies to attack the pathogen
What are the cons of vaccines?
1) They don’t always 100% work
2) You can have a bad reaction to them e.g. swelling
3) It can be expensive to make vaccines and carry out a vaccination program
How can you detect a disease in the field?
You can observe the symptoms of someone / something and link that to a particular disease
State 4 ways you can detect a disease in a lab
1) You can count the number of cells
2) You can view the sample under a microscope
3) You can grow the sample in a culture
4) You can sequence and analyse the genetic material
Why can counting the number of cells in a sample help detect a disease?
Some diseases change the number of red blood cells in a given volume, therefore if this could be used to detect whether a disease known to do this is present.
Also you can count the number of white blood cells, and if it is below the normal amount, that can indicate the organism is fighting off a disease
Why can viewing a sample under a microscope help detect a disease?
Under a microscope, you may be able to detect particular microorganisms from their appearance.
Also staining then viewing can help identify pathogens e.g. some bacteria will absorb the dye, while other won’t
Why can growing a sample in a culture help detect a disease?
Sometimes there won’t be enough of the pathogen in a sample for it to be detected, therefore by growing it further, it will make it easier to detect and identify
Why can sequencing and analysing a sample help detect a disease?
Scientists have worked out the genomes of many different pathogens, and can find out if a specific pathogen is present by adding a complementary section of DNA which if the pathogen is present will bind to it and identifying the pathogen
State the 2 types of culture mediums
Nutrient broth solution and agar jelly
How do you make an agar plate?
1) Hot jelly agar is poured into a Petri dish
2) When the jelly sets, an inoculating loop is used to transfer the microorganisms
3) The microorganisms then multiply
What is a common control used in testing antibiotics in agar jelly and why?
Often, a single, non-antibiotic soaked paper disk is put in the agar jelly alongside the antibiotic soaked ones to ensure that any difference in bacteria growth around antibiotic soaked disks is due to the antibiotic, not anything else (e.g. something in the paper)
How can monoclonal antibodies be used to detect and identify pathogens?
Monoclonal antibodies specific to a certain pathogen can be made, and then attached to a dye. The monoclonal antibodies can then be mixed with a sample which could contain the pathogen, and if the dye is triggered, then the pathogen is present
How can monoclonal antibodies be used to treat disease?
Since monoclonal antibodies can be designed to specifically target a certain cell type, you can use them to label specific cells for destruction by the immune system. This is useful as cancer cells are not seen as foreign to the immune system so aren’t attacked by the immune system, however through the use of monoclonal antibody labeling for destruction, they can be targeted and destroyed by the immune system
Alternatively they can target anti-cancer drugs to cancer cells- these may be radioactive or toxic. This means that the cancer cell will be destroyed, but the surrounding cells will not.
What is a disease risk factor?
A thing that increases the chance of getting that disease
What are painkillers?
Drugs that do tackle the cause of the disease, but rather relieve the symptoms
What are antibiotics?
Medicine that kill or inhibit growth of harmful bacteria without harming your own body cells- they are made naturally by fungi and cultured on a large scale in the lab
What are antivirals?
Medicine that does not destroy the targeted virus; instead they inhibit their development- they are difficult to produce because it is hard to target a virus without damaging normal cells
What is the effect of overusing antibiotics and not completing the course?
Some bacteria are naturally more resistant to certain antibiotics- the misuse and overuse of antibiotics can increase the number and rate of development of resistant strands.
For example if a person is prescribed a course of antibiotics, and they do not finish it, the most resistant bacteria will still remain. As the majority of the weaker bacteria is gone, this will leave the resistant bacteria with lots of space and nutrients, allowing it to replicate and make more resistant bacteria rapidly.
The more this happens, and the more often antibiotics are used, the more bacteria is going to be immune to more antibiotics, eventually possibly creating a super bacteria, which is immune to everything
What are the direct causes of CVD?
High blood pressure and lots of LDL cholesterol
How does high blood pressure and lots of LDL cholesterol lead to coronary heart disease?
They cause the build up of fatty deposits inside arteries, narrowing them- over time, these hardens forming atheroma. These restrict blood flow.
How are heart attacks and strokes caused?
Complete blockage of arteries by atheroma or blood clots can cause heart attacks, where part of the heart lack oxygen. If the blockage occurs in the brain then it can cause a stroke
State 3 medicines that can be used to treat CVD and what they do
Statins reduce the level of cholesterol present in the bloodstream but can have serious side effects e.g. kidney failure, liver damage and memory problems
Anticoagulants make blood clots less likely to form but if you are cut excessive bleeding will occur
Antihypertensives reduce blood pressure but can cause headaches or fainting
State 3 surgical procedures to treat CVD and how they work
Stents are tubes that can be implanted inside arteries, keeping them open, however over time can make scar tissue grow
Coronary bypass surgery is where a piece of healthy vessel from elsewhere can be used to bypass a blocked artery
A whole heart can be replaced from someone who is dead, however this can have problems as it does not always start pumping properly and could be seen as foreign by your immune system therefore rejected
What occurs in preclinical testing?
Drugs are tested on cultured human cells, then on live animals
What occurs in clinical testing?
Drugs are tested on healthy human volunteers, then on real patients
