microorganisms

• cooking - kills microorganisms by denaturing their enzymes. microbes can't survive high temperatures and are so removed from the food.
• pickling - the acidic pH kills microbes on the food and means that no new ones can survive. the acid denatures the microbes' enzymes
• pasteurising - kills microbes using heat and pressure. the higher temperatures denature the microbes' enzymes
• microorganisms = microscopic organisms that can only individually be seen by using a microscope
• aseptic technique is reduced to reduce risk of contamination. it means using sterile methods that prevent contamination from unwanted organisms
• bacteria :

  • living
  • 2 micrometres
  • reproduce by binary fission. mother cell is identical to daughter cell
• canning - microbes on the food are killed first using heat. when the can is sealed there is no oxygen for the microbes to sruvive
• curing - dehydrates the food and microbes on it. microbes need water to survive
• chilling/freezing - colder temperatures slow down reactions in the microbes' cells, which slows down the reproduction and growth process.
• viruses:

  • not living
  • 20-800 nanometres
  • reproduce by taking over other cells and using them
• fungi:

  • living
  • 2-10 micrometres
  • reproduce by forming fruiting bodies that release spores
• animals, dogs (rabies) - bitten by an infected animal, virus seeps through cut
• digoxin = controls heart problems, comes from foxgloves
• bodily fluids - sharing needles/syringes, sex with an infected person
• animals, insects (malarial) - spread by infected mosquitos when they bite
• pathogen = a microorganism that may cause disease
• aspirin - painkiller for pains like headaches and lowering fever, comes from bark of a willow tree
• contaminated food(food poisioning) = eating food with harmful bacteria, undercooked/unwashed food
• direct contact = skin to skin contact, wet moist conditions
• contaminated water (cholera) =consuming dirty water
• airborne - sneezing, mucus carries the virus into the air which is then breathed in by others
• anti-depressants = treats depression, comes from St John's wart
• morphine = blocks pain signals to the rest of the body, comes from poppy opium
• work in a sterile working zone = bunsen burners can create a sterile working zone by reducing the risk of contamination from the air
• store agar plate upside down = during incubation period agar plates are stored upside down to prevent condensation droplets falling onto the agar, causing contamination
• sterilise all equipment before use = sterilising helps kill unwanted microorganisms and prevents contamination
• flame the inoculating loop

  1. place loop in a flame to sterilise
  2. once removed leave in sterile working area to cool
  3. needs to cool whilst remaining sterile