1. DISEASE IN HUMANS  Types of disease can be categorised in many different ways.  Looking at CAUSE of disease the three main groups are:  Biological agents including micro-orgs  Faulty genes (inheritance)  Environmental factors Note: Generally both inherited and environmental diseases are also classed as

2. 1. Prevention Throughout history, particularly since Victorian times, advancements have been made to deal with disease. Prevention:

3. 2. Treatment Throughout history, particularly since WW2, advancements have been made in ways to treat disease. Treatments:

4. Problems continue…… Despite these advance ‘we’ still have major problems with fighting disease.  Antibiotic resistance in bacteria eg.  Disease caused by social influences: eg.  Viral diseases eg.

5. Infectious diseases  Caused by micro-organisms including: .. .. .. Disease may also be caused by parasitic macro-organisms  The spread of infectious diseases can be (and is) prevented using simple hygiene:

6. Bacteria Bacteria are prokaryotes. These are all single- celled organisms but their cells are very different to the animal and plant cells studied in Year 10:  No cell wall  No distinct nucleus (DNA in long strands and small ‘circles’ or plasmids)  Reproduce by ‘binary fission’  May produce harmful toxins eg. in TETANUS the toxin paralyses the jaw and thoracic muscles eg.

7. Fungi Yeasts, moulds, mushrooms etc were once classified as PLANTS, but now form a separate Kingdom ‘FUNGI’ WHY?......  Do not contain chlorophyll (no photosynthesis) so are…  Heterotrophic feeders, growing directly on ‘food’  Microscopic fungal threads or ‘hyphae’ grow into a ‘mycelium’ (visible mass of hyphae) on the food  Asexual reproduction (spores)

8. Viruses Viruses are so small that they are only visible using EM. They are considered to be non-living organisms. WHY?  Cannot perform MRS GREN  No cell, just a protein ‘coat’ containing DNA or RNA  Reproduce by taking control of a cell’s DNA

9. Parasites  ‘Larger’ organisms (including protoctista) which live on/in a host organism. Note: the host does not benefit in any way from the presence of the parasite eg protoctista: worms: insects:

10. HIV  Human Immunodeficiency Virus  Contracted by sexual contact or direct transfer of body fluids eg. shared needles of drug users  Infects and destroys the immune system, specifically white blood cells (lymphocytes), preventing the production of antibodies  Body becomes susceptible to invasion from other micro-organisms leading to……..AIDS

11. AIDS  Acquired Immune Deficiency Syndrome  People with HIV eventually die from a collection (syndrome) of diseases that their immune system cannot prevent or fight off eg

12. Preventing HIV and AIDS  Unless tested a person may be unaware for many years (8+ on average) that they are infected with HIV  During this time they may unknowingly infect others  Precautions should be taken: .. .. ..

13. Fighting Disease - Antiseptics  Chemicals used to kill micro-organisms on the SURFACE of the skin  Very useful for pre-surgical cleansing to avoid micro-organisms entering body  Very useful for cleaning surfaces/equipment to be used in surgery  But in some cases can delay healing as may destroy body cells as well as micro- organisms

14. Fighting Disease - Antibiotics  Drugs that kill or slow down the growth of bacteria INSIDE the body (Antibiotics do not affect VIRUSES)  Antibiotics are produced naturally by fungi and plants and were first discovered by Alexander Fleming in 1928. With Chain and Florey the first antibiotic, penicillin, was manufactured for public use  Many strains of bacteria are developing antibiotic RESISTANCE QHow does antibiotic resistance develop?  Infections like MRSA will become more common unless antibiotic resistance is reduced QHow can antibiotic resistance be reduced?

15. Fighting Disease – New Solutions  New antibiotics – expensive and slow and bacteria will soon develop resistance again  Chemically alter existing drugs (antibiotics) – bacteria will soon develop resistance again  Phage technology, using specific viruses to attack and kill bacteria QWhat are the possible advantages and disadvantages of using phage technology

16. Preventing disease - Immunity  Immunity – the means by which the body protects itself from disease  Active Immunity – long lasting immunity acquired as a result of the disease itself or a vaccination against it  Passive Immunity – short lived immunity from introducing antibodies into the body eg

17. Preventing disease - Immunisation Immunisation – where the body is encouraged to make specific antibodies Artificial immunisation uses vaccination HOW DOES IT WORK? 1.A dead or mild form of a pathogen is introduced into the body (often by injection) 2.The body produces specific antibodies in response to the dead/mild form of the pathogen 3.If a virulent form of that pathogen then invades the body the specific antibodies are ready to destroy it Note: Edward Jenner produced the world’s first vaccine against SMALLPOX in 1796 using cowpox virus

18. Artificial Immunisation - Problems  Pathogens may mutate so that antibodies will no longer ‘fit’ to fight the disease eg the common cold  There are very small risks involved in introducing pathogens into the body (even mild or dead ones!) therefore…  Some people chose not to be vaccinated thus increasing the risk of disease spreading (by reducing ‘herd immunity’)  The risks from the disease are much greater than the risks from vaccination

19. Useful pathogens Biological control is the use of living organisms to control pests: - [Predators] - [Parasites] - Disease (pathogens) a pollution-free alternative to using pesticides long lasting and organic pest control eg Disadvantage– organisms can develop immunity

20. DISEASE IN PLANTS  Plant diseases cause economic problems  Interventions and legislation have been introduced to reduce the problems: Chemical treatments Selectively breeding resistant varieties Crop rotation Change to sowing times Grafting crops onto disease resistant root stock Laws against growing susceptible varieties Laws against transporting infected material  Explain how each of these points may prevent the effect of a disease  Any other suggestions?

21. Example: Potato Blight This disease caused the ‘potato famine’ in Ireland in 1846 resulting in many Irish people moving to America to find work and food  A fungus that attacks potatoes via the leaves  Fungal spores germinate on the leaves and grow into the plant destroying cells  Spores remain in the soil for future crops Current treatments:...