vaccines

• how does a person become immune

  memory T lymphocytes remember the specific antigen and will recognise it a second time round

  memory B lymphocytes record the specific antibodies needed to bind to the antigen

  now the immune system can respond quickly to a second infection
• what is the secondary response


  If the same pathogen enters the body again, the immune system will produce antibodies quicker and in larger amounts
• 3 differences between the primary and secondary response

  primary: slow secondary: fast ( clonal selection is faster)

  primary: B and T lymphocytes activated secondary: memory cells activated

  primary: symptoms secondary: no symptoms

  primary: less antibodies secondary: more antibodies
• what is an antibody

  a Y-shaped glycoprotein made by a plasma B lymphocyte in response to a foreign antigen
• function of the variable region on antibodies

  allows binding to complementary antigens --> 2 variable regions allow binding to more than 1 antigen
• function of the hinge region on antibodies

  allows flexibility when binding to antigen
• function of the constant region on antibodies

  allows binding to receptors on immune system cells e.g. phagocytes
• function of the disulfide bridge on antibodies

  holds the polypeptide chains together
• structure of antibodies?

  made of 4 polypeptide chains - 2 heavy chains and 2 light chains. each chain has a variable region and a constant region
• what are the 3 roles of antibodies

  agglutination

  neutralisation

  opsoninisation
• what is agglutination

  agglutinins bind to multiple antigens causing them to clump together:

  - pathogens now can't attach to hosts cells or tissues

  - too large to cross hosts cell membranes

  - can't move as much so more likely to be ingested by phagocytes
• what is neutralisation

  antitoxins bind to toxins produced by pathogens preventing them from affecting human cells so the toxins are neutralised and the toxin-antibody complexes are phagocytosed
• What is opsonisation by antibodies?

  opsonins increase the likelihood of phagocytosis:

  - their variable regions bind to the antigens

  - their constant regions bind to the phagocyte
• what is active immunity

  your immune system makes its own antibodies after being stimulated by an antigen
• what is natural active immunity

  When you become immune after catching a disease
• what is artificial active immunity


  when you become immune after being given a vaccination containing a harmless dose of antigen
• what is passive immunity

  immunity from given antibodies made by a different organism
• what is natural passive immunity

  Passing antibodies from mother to baby through the placenta and in breast milk
• what is artificial passive immunity

  When you become immune after being injected with antibodies from someone else
• 4 differences between active and passive immunity

  active: requires exposure to antigen

  active: takes a while for protection to develop, passive: protection is immediate

  active: long-term protection passive: short-term protection

  active: memory cells produced passive: none produced
• what are autoimmune diseases

  a disease resulting from an abnormal immune response
• what are autoimmune diseases caused by

  the immune system is unable to recognise self-antigens so it treats self antigens as foreign antigens, launching an immune response against itself
• example of autoimmune disease

  arthritis: immune system attacks cells in joints causing pain and inflammation
• are autoimmune systems long or short term + how are they cured

  long term

  can't be cured, only treated
• what is the function of vaccines

  they contain substances that cause the immune system to produce memory cells against a particular pathogen, without the pathogen causing disease --> so you become immune without having symptoms
• how do vaccinations prevent epidemics

  if a large percentage of the population is vaccinated, people who haven't been vaccinated are unlikely to get the disease --> herd immunity
• what are vaccines made of

  antigens which could be dead or attenuated pathogen or could be other molecules such as mRNA that code for antigens
• what are booster vaccines for

  to make sure memory cells are produced
• what are routine vaccines

  vaccines offered to everybody e.g. MMR
• why might a new vaccine be made e.g. influenza

  the antigens on the pathogen change, forming new strains
• what are antibiotics

  chemicals that kill or inhibit the growth of bacteria
• what was the first antibiotic to be discovered + when

  penicillin causing the wide use of antibiotics in the mid-20th century
• benefits of antibiotics

  bacterial infections can be easily treated so death rates have fallen dramatically
• disadvantage of antibiotics

  they can become antibiotic resistant so aren't killed by antibiotics --> increased use of antibiotics means resistance is more common so we are less able to treat some life-threatening bacterial infections
• many medicinal drugs are manufactured using natural compounds found in plants, animals or microorganisms e.g. penicillin is obtained from a fungus
• what are the possible sources of medicines?

  only a small proportion of organisms have been investigated so far, so it's possible that plants and microorganisms exist that contain compounds that could be used to treat currently incurable diseases - others may produce antibiotics
• possible sources of drugs need to be protected by maintaining the biodiversity on earth --> if we don't protect them, some species could die out before we get a chance to study them
• what are personalised medicines?

  • medicines that are tailored to an individual's DNA. the theory is that if doctors have your genetic information, they can use it to predict how you will respond to different drugs and only prescribe the ones that will be most effective for you
  • scientists hope that by studying the relationship between someone's genetic make-up and their responsiveness to drugs, more effective drugs can be produced in the future