biology

• Microorganisms


  Lifeforms that can only be seen with the help of a microscope
• Microorganisms


  • They can cause serious disease in humans
  • They can be harnessed and used for our benefit
• Biotechnology


  The process of using microorganisms in food production
• Examples of biotechnology in food production

  • Using yeast to make bread
  • Using bacteria to produce yogurt
• Yogurt production


  1. Sterilization of equipment

  2. Pasteurization of milk

  3. Addition of lactobacillus bacteria

  4. Incubation and fermentation

  5. Cooling and thickening
• Pasteurization


  Heating milk to 72 degrees C for 15 seconds, then rapidly cooling it, to kill any bacteria
• Fermentation


  The process where lactobacillus bacteria convert lactose to lactic acid
• Lactic acid


  The waste product of fermentation that gives yogurt its sour taste
• Sterilization is very important to prevent unwanted harmful bacteria from growing
• The only bacteria added are the lactobacillus bacteria
• The fermentation and lactic acid production causes the milk to solidify into yogurt
• Cooling the yogurt results in a thick, tangy final product
• Fruits or flavors can be added to the final yogurt product
• Features that all living organisms share

  • Movement
  • Respiration
  • Sensitivity
  • Nutrition
  • Excretion
  • Reproduction
  • Growth
• Organelles that both animal and plant cells share

  • Cell membrane
  • Cytoplasm
  • Nuclei
  • Nucleus
  • Ribosomes
  • Mitochondria
• Additional organelles in plant cells

  • Cell wall
  • Vacuole
  • Chloroplasts
• Nucleus


  Controls the activities of the cell
• Cytoplasm


  Where chemical reactions take place
• Cell membrane


  Controls what enters and leaves the cell
• Ribosomes


  Where protein synthesis takes place, where proteins are made
• Cell wall


  Made of cellulose, protects and supports the cell
• Vacuole


  Filled with cell sap, helps maintain the structure of the cell
• Chloroplasts


  Contain the green pigment chlorophyll, where photosynthesis takes place
• Eukaryotes


  Animal cells, contain membrane bound organelles such as nuclei and mitochondria
• Prokaryotes


  Viruses and bacteria, contain no membrane bound organelles, have strands of DNA or RNA instead of a nucleus
• Bacterial cell


  • Sometimes has a cell wall
  • Sometimes has a slime capsule
  • Sometimes has a flagella to help it move
  • Has a circular chromosome instead of a distinct nucleus
  • Has plasmids - small rings of genetic material
• Types of bacteria


  • Pathogenic (cause disease)
  • Non-pathogenic (useful, e.g. in yoghurt making)
• Bacteria are unicellular, made of one cell only
• Viruses


  • Much smaller than bacteria
  • Simply made of a protein coat containing either DNA or RNA
  • Have no typical organelles
  • Are non-living, do not excrete, respond, grow, or reproduce
  • Are always pathogenic, there are no 'good' viruses
• Viruses

  • Flu virus
  • Cold virus
  • HIV (causes AIDS)
  • Tobacco mosaic virus (causes discoloration in plant leaves)
• Protists

  • Some have animal cell properties, some have plant cell properties
  • Some have chloroplasts (more plant-like), some don't (more animal-like)
  • Use diffusion to obtain nutrients and oxygen
• Protists


  • Algae
  • Amoeba
  • Plasmodium (causes malaria)
• Fungi

  • Similar to plant cells but more circular
  • Have a cell wall made of chitin
  • Have a cell membrane, cytoplasm, vacuole
  • Do not have chloroplasts
• Saprotrophic nutrition

  Fungi secrete enzymes onto dead matter which break it down, and then they absorb the nutrients
• Fungi


  • Yeast
  • Mushrooms
• Fungi have thread-like structures called hyphae that form a network called mycelium
• Five kingdoms of life

  • Plants
  • Animals
  • Protists
  • Bacteria
  • Fungi
• Carbohydrate storage


  In animals - glycogen

  In plants - starch

  In fungi - glycogen
• Cell


  A group of organelles working together to perform the same function
• Tissue


  A group of cells working together to perform the same function