Preventing and Treating Diseases

• What are antigens?


  Unique proteins on the surface of every cell. The ones on microorganisms are different to the ones in your body and the immune system recognises that.
• What are memory cells?


  Cells that remember a specific antigen so that if it returns, the body can quickly respond
• How do vaccinations work? (3)


  1) Small amounts of dead/inactive pathogens are put into your body

  2) The antigens in the vaccine stimulate white blood cells into antibodies and they do their thing

  3) You are immune to future infections by the pathogen.
• What is herd immunity?


  When a majority of a population are vaccinated against a disease. This means that even people who have not been vaccinated are less likely to get it because there are fewer people to catch it from.
• What is the difference between antiseptics, antibiotics, and antibodies?


  Antiseptics - kill microorganisms in the environment

  Antibiotics - kills bacteria in the body

  Antibodies - made by white blood cells to destroy pathogens
• What can you use to kill bacterial?

  Disinfectants and antiseptics outside of the body
• How do painkillers treat symptoms?


  They relieve headaches and sore throats but they do not kill pathogens
• How do antibiotics work?


  They damage the bacterial cells without harming your own cells. Sometimes they are put directly into your bloodstream when you a really ill to make sure they reach the cells ASAP
• What are the problems with antibiotics? (2)


  1) They can't kill viral pathogens so they have no effect on diseases caused by viruses.

  2) Strains of bacteria that are resistant to antibiotics are evolving
• Why are viruses hard to develop drugs for?


  Viruses reproduces inside the cells so it's difficult to develop drugs that will kill the viruses without damaging the cells and tissues
• How was penicillin discovered?


  Fleming was studying petri dishes and noticed that mould killed a bacteria growing in the dish
• What are the elements of a good medicine? (4)


  1) Effective

  2) Safe - not too toxic or have unacceptable side effects

  3) Stable - must be able to take the medicine under normal conditions and store it for some time

  4) Successfully taken into and removed from the body
• What steps do drugs undergo to see if all conditions are met to make them a good drug? (5)

  Preclinical testing

  1) They are tested on cells, tissues, and sometimes whole organs

  2) They are tested on animals to see how they work on whole organisms and this is used to observe any possible side effects

  Clinical trials

  3) Tested on healthy volunteers and patients using low doses at first to check for side effects

  4) If safe it is tried on a small number of patients and if it's safe and effective bigger clinical trials take place to find the optimum dose for the drug

  5) If it passes all legal tests it is licenced and able to be prescribed by doctors
• What is a double blind trial?


  When both the doctors and patients are unaware of which patients are given a placebo or real drug
• What are monoclonal antibodies?


  Proteins that target particular cells or chemicals in the body
• How are monoclonal antibodies produced? (4)


  1) B lymphocytes (can't divide but can make specific antibodies) combine with tumour cells (divide rapidly but can't make specific antibodies) to make hybridoma cells

  2) The hybridoma cells are divide making a large number of identical cells

  3) The antibodies are collected and purified
• What are the 5 main uses of monoclonal antibodies?


  1) Pregnancy tests - monoclonal antibodies bind to HCG (pregnancy hormone) if it is present

  2) Diagnosis of disease - monoclonal antibodies carrying markers bind to specific antigens found on pathogens/blood clots making it easy for doctors to see where they've built up

  3) Measuring and monitoring levels of hormones and other chemicals in the blood|

  4) Research - they identify specific molecules in a cell/tissue and when they bind to the desired molecules scientists can see what has happened by observing the build-up of fluorescence

  5) Treating disease
• How do pregnancy tests work? (4)

  1) Urine reaches the reaction zone where antibodies bind to any HCG. The antibodies have dye molecules. The urine picks up AB1 enzymes to the test zone.

  2) More antibodies bind to one of the HCG's 5 binding sites. If HCG is present it gets sandwiched between the AB1 and AB2 enzyme sticking to the test zone allowing the dye molecules to activate and create a visible pattern

  3) All unbound AB1 enzymes end up at the control zone and more dye molecules are activated
• What are 3 ways monoclonal antibodies can be used to treat cancer?


  1) Direct use of the antibodies trigger the immune system to recognise, attack, and destroy cancer cells

  2) The antibodies can block receptors on the surface cells to stop them from growing and dividing

  3) The antibodies can be carry toxic drugs/radiation substances/ chemicals to stop the cells from growing and dividing by attacking the cells directly without damaging the cells inside your body
• What are the pros and cons of monoclonal antibodies?


  Pros:

  - Only bind to the specific diseased/damaged cells so healthy ones aren't effected at all

  - Specificity of monoclonal antibodies means they can treat a wide range of conditions

  
  

  Cons:

  - Expensive to develop

  - If they carry drugs through the blood they can still harm the surrounding tissue