bio Health and disease (topic5)

• Health


  The state of complete physical, mental and social well-being and not merely the absence of disease or infirmity
• Multiple different aspects of health need to be considered
• Pathogen


  Microorganism that causes disease
• Disease


  A condition where part of an organism doesn't function properly
• Types of disease


  • Communicable
  • Non-communicable
• Communicable disease


  • Can spread from person to person
  • Caused by pathogens (virus, bacteria, fungi)
• Non-communicable disease


  • Cannot be transmitted between individuals
  • Can be hereditary
• Susceptibility to disease


  Presence of one disease can lead to higher susceptibility to other diseases
• HIV


  Weakens immune system by destroying white blood cells, making the body more susceptible to other diseases
• Types of pathogens


  • Virus
  • Bacteria
  • Fungi
  • Protists
• Pathogens: common infections and their pathogens

  • Cholera- bacteria -causes diarrhoea spread by water
  • Tuberculosis-bacteria -causes lung damage - spread airbourne
  • Chalara die ashback- fungi - causes leaf loss + bark lesions - spread airborne
• Lytic pathway of virus lifecycle

  1. Virus enters cell

  2. Virus uses cell's machinery to replicate its genes

  3. New viruses assemble

  4. Cell bursts to release new viruses
• Sexually transmitted infections (STIs)

  • HIV-virus
  • Gonorrhoea-bacteria
• HIV


  Virus that destroys white blood cells, leading to AIDS
• How to reduce/prevent spread of STIs

  • Improve hygiene and handwashing
  • Reduce contact with infected individuals
  • Vaccinations
• Plant physical barriers against disease

  • Thick waxy cuticle
  • Cell walls made of cellulose
• Plant chemical barriers against disease


  • Produce chemicals that deter pests (insects) from feeding
• Detecting and identifying plant diseases

  1. Visual inspection

  2. Laboratory-based diagnostic testing
• Laboratory-based diagnostic testing


  • Detecting antigens unique to a pathogen
  • Detecting pathogen's DNA
• Monoclonal antibody testing for plant diseases

  1. Take cuttings from diseased plant

  2. Grow pathogen on culture medium

  3. Test and identify pathogen using monoclonal antibody testing
• Immune response


  Pathogens have antigens that trigger B-lymphocytes to produce antibodies specific to those antigens, which then bind to and destroy the pathogen
• Human physical barriers against disease

  • Mucus
  • Cilia
  • Skin
• Human chemical barriers against disease

  • Lysozymes - found in white blood cells to kill and digest bacteria
  • Hydrochloric acid - found in stomach to kill bacteria in food reaching stomach to prevent infection
• Secondary immune response


  Faster and stronger response when exposed to same pathogen again, due to memory lymphocytes
• Immunisation/vaccination


  Injecting dead/inactive pathogens to trigger production of antibodies and memory lymphocytes
• Advantages of immunisation


  • Herd immunity
  • Eradication of some diseases
• Disadvantages of immunisation


  • Immunity not guaranteed / effective
  • Potential bad reactions like fevers
• Aseptic technique


  Sterilising equipment and growth medium to prevent contamination by microorganisms
• Investigating effects of antiseptics and antibiotics

  1. Grow bacterial culture

  2. Apply antibiotics/antiseptics and measure inhibition zones
• Developing new medicines


  1. Drug discovery

  2. Preclinical testing

  3. Clinical testing
• Placebo


  Looks like the real drug but has no active ingredients, used to test if the real drug is actually effective
• Monoclonal antibodies


  Identical antibodies made from a single type of cell, bind to a specific antigen
• Producing monoclonal antibodies


  1. Inject antigen into animal

  2. Isolate antibody-producing B-lymphocytes

  3. Fuse with tumour cells to form hybridoma cells

  4. Hybridoma cells divide rapidly to produce monoclonal antibodies
• Non-communicable disease


  Caused by interaction of lifestyle factors, genetics, and nutritional deficiencies
• Examples of non-communicable diseases

  • Cardiovascular disease
  • Cancer
  • Liver disease and diabetes
• Risk factors for non-communicable diseases

  • High fat intake
  • Smoking
  • Alcohol intake
  • Lack of exercise
  • Obesity
• Cardiovascular disease treatment


  • Lifelong medication
  • Surgical procedures like stents
  • Lifestyle changes
• Lysogenic pathway

  1. virus injects it‘s genetic material into host cell
  2. virus’s genetic material integrates into host cell’s genome/DNA
  3. the new viral genetic material gets replicated along with host DNA
  4. eventually a trigger causes the viral genetic material to leave the genome and enter the lytic pathway
• Uses of Monoclonal antibodies

  1. pregnancy tests
  2. analyse blood in labs
  3. in cancer treatment
• Pregnancy tests using monoclonal antibodies

  1. Urine contains human chorionic Gonadotroph (hCG) hormone

  2. First section of test has complementary antibodies to hCG that can move and are attached to blue beads

  3. Second section has fixed antibodies complementary to hCG

  4. Urine applied to first section

  5. hCG binds to moveable antibodies attached to blue beads

  6. Mixture moves along strip

  7. Carried to second section

  8. Fixed antibodies bind to hCG and blue beads

  9. This indicates pregnancy