B3-Infection and response Flashcards
What is a pathogen?
A micro-organism that causes disease
What is the difference between communicable and non-communicable diseases?
Communicable diseases can be passed from one person to another
Non-Communicable diseases cannot be transmitted from one person to another
What are the 4 types of pathogens?
- Viruses
- Bacteria
- Fungi
- Protists
How do bacteria cause disease?
They divide rapidly (called binary fission) and in the process produce toxins-this can make the host feel ill and can damage cells
What are some features of viruses?
A protien coat with a strand of DNA inside
How do viruses cause disease?
They enter the body’s cells and once replicating, they explode the cell-the damaged cells cause the symptoms
How are pathogens spread (3)
- By air
- Direct contact
- By water
How do you sterilise the inoculating loop before use?
By heating it until it is red hot
Why should cultures be incubated at a maximum temperature of 25°?
To reduce the likelihood of pathogens growing that might be harmful to humans
Why should the petri dish only be partly sealed with tape?
To prevent microorganisms from the air from contaminating the culture and to allow some air in to prevent harmful anaerobic bacteria from growing
Why is agar gel needed when growing bacteria in petri dishes?
It contains carbohydrate as an energy source, some minerals and nitrogen so the bacteria can make proteins
Why are petri dishes stored upside down?
To stop condensation falling on the agar surface
What are the ways to protect bacterial growth?
- To raise or lower the temperature
- Using chemicals such as disinfectants, antiseptics (safe to use on our skin), antibiotics (safe to use in our bodies)
How do you calculate the effect of disinfectants and antibiotics on bacterial growth?
By measuring the area of the zone of inhibition
How can the spread of disease be prevented? (4)
- Simple hygiene measures
- Destroying vectors
- Vaccination
- Isolating infected individuals
What are 3 examples of viral diseases?
- Measles
- HIV/AIDS
- Tobacco mosaic virus
How are measles spread?
By droplet infection
What are the symptoms of measles?
A fever and a red skin rash-it can also cause blindness and brain damage and be fatal
How can measles be cured/prevented?
It can’t be cured however vaccination and isolation of patients prevent the spread
How is HIV spread?
By sexual contact or by exchange of bodily fluids
What are the symptoms of HIV?
Mild flu like sumptoms
What does HIV do?
It attacks the immune cells and after the initial mild illness it is hidden inside the immune system unil the immune system is so badly damaged that it can no-longer deal with infections or certain cancers-now it is called AIDS
How can we prevent the spread of HIV?
By using condoms, not sharing needles, screening blood used for transfusions and bottle feeding children in the case of HIV-positive mothers
How is Tobacco mosaic virus spread?
Via contact and vectors
What are some symptoms in plants of Tobacco mosaic virus?
It causes a ‘mosaic pattern’ of discoloration on the leaves as the virus destroys the cells-this reduces photosynthesis and affects the growth of the plant
How can the spread Tobacco mosaic virus be prevented?
Good field hygiene and good pest control
What are 3 examples of bacterial diseases?
- Salmonella
- Gonorrhoea
- Plant bacterial diseases-Agrobacterium tumefaciens
How is salmonella spread?
Through undercooked food and poor hygiene
What are some symptoms of Salmonella?
Fever, Abdominal cramps, Diarrhoea
How can the spread of Salmonella be reduced?
Vaccinating poultry against it, Avoid washing raw chicken, Wash hands after handling raw chicken
How is Gonorrhoea spread?
Through unprotected sexual contact with an infected person
What are symptoms of Gonorrhoea?
Thick yellow or green discharge from genitals, pain while urinating, long term pelvic pain, infertility and ectopic pregnancies
How can the spread of Gonorrhoea be reduced?
By limiting sexual partners and using barrier contraception
How does Agrobacterium tumefaciens infect plant cells?
By inserting plasmids into plant cells
What are some examples of fungal diseases?
- Athletes foot
- Rose black spot
How is rose black spot spread?
Via spores of the fungus
What are some symptoms of rose black spot?
Purple or black spots to develop on rose leaves-this causes the leaves to turn yellow, drop off early and this weakens the plant-the plant doesn’t flower well
How can we prevent the spread of rose black spot?
By using chemical fungicides or breeding relatively resistant roses to the disease
What is malaria an example of
A protist
What causes malaria?
A parisite called plasmodiun
How is malaria transmitted?
Mosquitos bite the organism who has plasmodium and then injects some saliva containig plasmodium to another victim-to stop the blood clotting
What is a mosquito an example of?
A vector
What are some symptoms of malaria?
Fevers, shaking, damage to blood and liver cells
How can the spread of malaria be prevented?
- Using insect nets
- Using insecticides to kill mosquitos
- Removing or poisoning stading water-where mosquitoes breed
- Taking antimalarial drugs-however these have to be taken 2 days before every day up to 4 weeks after and it causes side effects
What external defences are there to prevent microorganisms from getting inside the body?
- The skin acts as a barrier and produces antimicrobial secretions
- Nosehair
- Earwax
- Stomach acid
- The trachea and bronchi are liined with hairs called cilia and mucus
What are the 3 different roles/types of white blood cells?
- Ingesting micro-organisms
- Producing antibodies
- Producing antitoxins
What type of white blood cell produces antibodies and antitoxins?
Lymphocytes
What type of white blood cell ingest the micro-organisms?
Phagocytes
How does a lymphocyte produce antibodies?
- Firstly the Lymphocyte recognises the antigen-the memory cell
- Chemicals are released that cause the lymhpocytes to divide
- Through differentiation plasma cells are formed that produce 1000s of antibodies
- The antibodies latch onto and kill the bacteria or cause them to clump together
- Memory cells stay in the blood for future infections
Why are magnesium ions needed in plants and what symptoms are caused by deficiency?
- They are needed for growth and chorophyll production
- Yellow leaves, stunted growth, early leaf fall
Why are nitrate ions needed in plants and what symptoms are caused by deficiency?
- They are needed for protein synthesis
- Stunted growth
Why are phosphates needed in plants and what symptoms are caused by deficiency?
- They are needed for photosynthesis
- Dark blue/green leaves, inhibited shoot growth
Why is calcium needed in plants and what symptoms are caused by deficiency?
- It is needed for structural roles in the cell wall and membranes
- Bushy appearence of plants, Brown spots, inhibited growth
How can we detect diseases in plants?
By noticing symptoms such as stunted growth, discolouration and prescence of visible tests or by using testing kits that contain monoclonal antibodies
What are some physical plant defences?
- Thorns
- Tree bark
- Cellulous cell walls
- Spines
What are some chemical plant defences?
- Poisons
- Antibacterial secretions
- Nettle barbs
What are some mechanical plant defences?
- Curling leaves
- Leaf fall
- Mimicry
How do vaccinations protect against disease? (4)
1)Small amounts of dead or inactive pathogen are injected into the body
2)The antigens in the vaccine stimulate white blood cells into making antibodies
3)The antibodies destroy the pathogen without any risk of person getting the disease
4)The body is immune to future infections by the pathogen as the body now has memory cells and can respond quickly to create new antibodies
What are the key differences between active and passive immunity? (4)
- Active immunity-the body produces the antibodies
Passive immunity-a different person or animal produces the antibodies - Active immunity-works slowly
Passive immunity-works quickly - Active immunity-lasts for a long time after
Passive immunity-only lasts for a short time after - Active immunity-occurs after an illness or vaccination
Passive immunity-occurs after an injection or breastfeeding
What is herd immunity?
If a large proportion of the population is immune to a disease the spread of the pathogen in the population is much reduced
What caused the MMR vaccine controversy?
As the amount of vaccinated people against MMR increased so did cases of autism-this caused people to not want the vaccine. However this was just correlation as autism was being diognosed earlier as time went on.
What types of pathogens can vaccines kill?
Viruses and bacteria
Why do painkillers do and not do?
They relieve symptoms of disease but do not kill the pathogens
How can antibiotics cure bacterial diseases?
By killing bacteria inside your body
Why can’t disinfectants and antiseptics be used inside the body?
They are to poisonous
Why can antibiotics not kill viruses?
Viruses reproduce inside the cells and it is extremely difficult to develop drugs that will kill the viruses without damaging the cells and tissues of the body at the same time
Why can antibiotics not kill viruses?
Viruses reproduce inside the cells and it is extremely difficult to develop drugs that will kill the viruses without damahing the cells and tissues of the body at the same time
What is antibiotic resistance?
Where certain strains of bacteria are resistant to antibiotics
How does antibiotic resistance occur? (4)
1)Within a bacterial population there is variation caused by random mutations
2)This could lead to a bacteria becoming resistant to antibiotics
3)Due to the less-resistant bacteria being killed off there is less competition for the resistant bacteria and there is more space for the antibiotics to reproduce
4)Over time, the whole population of bacteria becomes antibiotic-resistant because the antibiotic-resistant bacteria are best suited to their environment
What are the 3 ways that bacteria can multiply?
- My reproducing DNA on death
- Binary fission
- Using conjugation these bacteria can share their genes
What are some ways to counter antibiotic resistance?
- By not using antibiotics for minor illnesses and infections
- By finishing the course of antibiotics
- By developing more powerful drugs
- By treating specific bacteria with specific antibiotics
Where were drugs traditionally extracted from?
Plants
Who was penicillin discovered by?
Alexander Fleming
What was and what was the issue caused by thalomide?
It was developed as a sleeping pill thought to be useful for easing morning sickness in pregnant women however it caused over 10,000 babies to be born with defects such as unformed limbs. It was later banned and caused drug testing to become more rigorous-it wasn’t tested on pregnant animals.
What are medical drugs tested for?
Toxicity (safety) , Efficacy and Dosage
What is the first stage in testing drugs and what is this testing?
Using computer models and skin cells grown from human stem cells in a laboratory-this allows the safety to be tested. Also, If the drugs damage the cells they fail the first test in preclinical drug trials
What is the second stage in testing drugs?
Drugs are now tested on animals such as rats to spot any side effects however it is illegal to test cosmetics or tobacco on animals
What is the third stage in testing drugs?
The clinical trial stage-this takes place over 3 phases:
1) Giving the drugs to a small amount of healthy volunteers (e.g. 20) to test for side effects
2) Giving the drugs to to a larger amount of patients (e.g. 200) to see if it treats the disease
3) Finally, the drugs are given to even more people (e.g. 2000) to find the optimum dosage
What are double blind trials?
Where a group of patients are either given the placebo or the new medicine. Neither the doctor nor the patients know who has recieved the real drug until the trial is complete-this is to test the placebo effect without any influence from the doctor.
What are hybridomas?
Cancer cells combined with antibody cells
How are monoclonal antibodies made?
1) The antigen is injected into the mouse
2) The mouse naturally produces Lymphocytes which produce antibodies specific to the antigen
3) Spleen cells which produce the lymphocytes are removed during a small operation
4) The spleen cells are fused with cancerous white blood cells called myeloma cells to form hybridoma cells which divide indefinitely-Detergent is added to the mixture to break down the surface membranes of both cells to help them fuse
5) These hybridoma cells divide and produce millions of monoclonal antibodies specific to the original antigen
What are and explain the uses of monoclonal antibodies?
- Pregnany tests-some monoclonal antibodies have been designed onto a hormone called HCG which is only found in the urine of pregnant women
- Cancer diagnosis and treatment-Cancerous cells have antigens and monoclonal antibodies can bind onto these antigens and cause cancerous cells to clump together making it easier to identify tumours which can then be treated or removed. Also monoclonal antibodies can be used to carry toxic drugs or radioactive substances for radiation therapy.
- Diagnosing other infections such as HIV and AIDS
- Research and locating specific molecules in cells by using monoclonal antibodies that link to a molecule of flourescent due
What does HIV stand for?
Human Immunodeficiency Virus
What does AIDS stand for?
Acquired Immune Deficiency Syndrome
What are 3 advantages of monoclonal antibodies?
- They only bind to the specific diseased or damaged cells-they don’t harm healthy cells
- They can be used to treat a wide range of conditions due to their specificity
- They have the potential to become very cheap in the future-cheaper than conventional drugs
What are 3 disadvantages of monoclonal antibodies?
- They aren’t as successful or as widely used as everyone hoped when they were first developed 40 years ago
- Producing the right monoclonal antibodies and attaching them to drugs and other compounds has proved more difficult than expected
- They are still expensive to produce
What are ethical issues of monoclonal antibodies?
- Production involves deliberately inducing cancer in mice
- Production also involves surgery of mice
- There is a debate about genetic engineering being used in mice as human genes to produce antibodies are placed in mice
- Testing can be seen as dangerous-in 2006 a drug trial took place in which 6 healthy volunteers organ failure
