Biology topic 3

• types of pathogens


  viruses,

  bacteria,

  parasites,

  fungi
• Bacteria


  single-celled organisms that lack a nucleus; prokaryotes
• Virus


  A tiny, non-living particle that invades and then reproduces inside a living cell, using its machinery
• protist


  A eukaryotic organism that cannot be classified as an animal, plant, or fungus.
• Fungi


  - single celled

  - hyphae

  - grow and penetrate human skin

  - hyphae can produce spores
• Ways pathogens can be spread

  - water

  - air

  - direct contact
• Measles


  - viral

  - spread by droplets

  - red skin rash

  - fever

  - can be fatal with complications

  - most people are vaccinated when young
• HIV


  - virus

  - sexual contact or exchanging bodily fluids

  - flu-like symptoms

  - attacks immune system cells

  - can turn into AIDS if untreated
• Tobacco Mosaic Virus (TMV)


  - affects plants

  - causes mosaic pattern on the leaves

  - parts of leaves become discoloured

  - cant carry out photosynthesis as well - affects growth
• Rose Black Spot


  - fungus

  - causes purple/black spots on leaves

  - leaves turn yellow - drop off

  - less photosynthesis

  - spreads through water or wind

  - treat by fungicides and stripping the effected leaves

  - the leaves need to be destroyed
• Malaria


  - protist

  - takes place inside a mosquito

  - mosquitos are vectors

  - cause fever

  - can be fatal

  - way to stop: stop mosquitos from breeding

  - use insecticides
• Salmonella


  - bacteria

  - causes food poisoning

  - fever

  - stomach cramps

  - vomiting

  - diarrhoea

  - caused by infected food

  - chickens given vaccination
• Gonorrhoea


  - Bacteria

  - STD/STI

  - passed through sexual contact

  - pain when urinating

  - green/yellow discharge

  - antibiotics

  - use protection
• Ways to reduce disease

  - Being hygienic

  - destroying vectors

  - isolating infected individuals

  - vaccination
• Body's defence system


  TRACHEA AND BRONCHI - secrete MUCUS which traps bacteria and pathogens also lined with CILIA to waft mucus

  STOMACH - produced HCL to kill pathogens

  SKIN - acts as a BARRIER and secretes anti microbial substances

  NOSE - HAIR and MUCUS trap pathogens
• Immune system


  The cells and tissues that recognize and attack foreign substances in the body
• Phagocytosis


  WBC engulf foreign cells and digest them

  
• Producing antibodies


  - pathogen has antigens on surface

  - WBC come across foreign antigen - start to produce proteins called antibodies

  - these lock onto invading cells so they can be found and destroyed

  - antibodies are specific to an antigen

  - antibodies then rapidly produced

  - if infected again the WBC will rapidly produce the antibodies to kill the pathogen.
• Producing antitoxins


  These counteract toxins produced by the invading bacteria
• How vaccinations work


  Syringe injects an dead/inactive form of a pathogen.

  White blood cells release antibodies to the specific antigen. They attach and clip pathogens together.

  Phagocytosis occurs.
• Vaccination Pros


  - Variety of vaccines protects you against many diseases

  - Memory cells can store antibodies needed for a long time

  - Means you can travel to exotic places

  - prevent epidemics
• Vaccinations cons


  - don't always work

  - can have a bad reaction
• Relieving symptoms of illness

  there to reduce symptoms not cure the illness

  - pain killers e.g. aspirin

  - cold remedies
• curing illness


  actually kill the pathogen (except virus)

  - antibiotics e.g. penicillin

  - different antibiotics kill different pathogens
• Anti-biotic resistant bacteria


  Mutated bacteria that are resistant to antibiotics:

  can grow rapidly

  will not be killed by the prescription medication
• Example of antibiotic resistant bacteria

  MRSA
• ways to reduce antibiotic resistant bacteria strains

  - avoid over prescribing

  - finish whole course of antibiotics
• Plant antibiotic: ASPIRIN


  FROM WILLOW
• Plant antibiotic: DIGITALIS


  FROM FOXGLOVE
• preclinical testing


  1) Is carried out on a potential new medicine in a laboratory using cells and tissues.

  - however cant uses these to trial drugs effecting whole or multiple organ systems.

  2) Moves onto testing on live animals:

  test for:

  EFFICACY - whether it works and produces desired effect

  TOXICITY - how harmful it is

  DOSAGE - concentration given and how often it should be given
• Clinical trials


  1) tested on healthy human volunteers, ensure no harmful side effects - very low dosage

  2) if results are good, move onto testing on people with the illness. OPTIMUM DOSAGE is found - dose most effective with least side effects

  3) patient split into 2 groups - one given drug, one given a placebo. Doctor can see actual effect of medicine - called a BLIND TRIAL

  4) often they are DOUBLE BLIND where patient nor doctor know which group is given the actual medicine - ensures NO BIAS.

  5) need to be PEER REVIEWED - helps to prevent false claims
• What is a placebo?

  a 'fake pill' that has no effect on the body - no bias
• what is the placebo effect?

  experimental results caused by expectations/phycological aspects
• How to make monoclonal antibodies

  1) inject a mouse with an antigen that will stimulate the mouse to produce antibodies against it

  2) B-lymphocyte cells are taken from the spleen

  3) Mix with a tumour cell

  4) form HYBRIDOMA cells

  5) divide rapidly to get lots of identical cells
• Monoclonal antibodies in pregnancy tests

  - Monoclonal antibodies are attached to the end of a pregnancy stick where a woman urinates

  - If she is pregnant, HCG will be present in her urine and will bind to the monoclonal antibodies which are specifically for binding to HCG

  - This causes a change in colour or patter which indicates pregnancy

  
• using monoclonal antibodies to treat cancer

  - Different cells have different antigens.

  - Cancer cells have antigens that aren't found on normal body cells. Called tumour markers.

  - In lab, monoclonal antibodies will bind to tumour markers.

  - An anti-cancer drug can be attached to these monoclonal antibodies which have radioactive substance or toxic drug stopping the cancer cells dividing.

  - Antibodies are given through a drip. They target specific cells bind to tumour markers.

  - Drugs kills the cancer cells but does not kill any normal body cells.
• using monoclonal antibodies to find specific substances

  - Monoclonal Antibodies bind to hormones and other chemicals in blood

  - test blood samples for certain pathogens

  - Locate specific molecules on a cell or in a tissue:

  1) monoclonal antibodies are made to bind to specific molecules

  2) these are bound to a fluorescent dye

  3)molecules present = monoclonal antibodies will attach to them and they can be detected because of the dye.
• advantages of monoclonal antibodies

  1)bind to only what needs treatment

  2)Healthy cells are not affected

  3)Can treat a wide range of conditions
• disadvantages of monoclonal antibodies

  1) created more side affects than expected

  2) difficult

  3) not as effective and successful as they once were
• Mineral ions deficiency in plants

  Plants NEED minerals, if they don't get them it can lead them to suffer deficiency symptoms.

  NITRATES: needed to make proteins and therefore growth - a lack of these cause STUNTED GROWTH.

  MAGNESIUM IONS: make chlorophyll, needed for photosynthesis. Without these plants suffer from chlorosis and have yellow leaves