B6a Summary

B6a Summary

1. BACTERIA

   • What are bacteria?
     • unicellular organsims
     • cells are just a few micrometres long
       • I µm = 0.001mm
         • micrometre = µm
     • plant & animal cells are 10X bigger
   • Classification of Bacteria
     • Rod
     • Curved Rod
     • Spherical
     • Spiral
   • Handling Bacteria
     • aseptic techniques
       • wear gloves
         • or wash hands before and after
       • disinfect working areas
       • sterilise all equipment
       • never leave lid off the containers
   • Bacterial Reproduction
     • Binary Fission
     • in ideal conditions bacteria reproduce every 20 minutes
       • after 4 hours you could have 4096 bacteria
     • consequences on health & food storage
       • will reproduce if left in warm conditions
       • put food in fridge
         • colder temp. slows enzyme activity and so slower reproduction
   • How do they feed?
     • consumption of organic nutrients
       • carbohydrates
       • proteins
     • some make own food
       • photosynthetic bacteria
       • hydrogen sulfide/ammonia to provide energy
         • to make food
         • e.g. chemoautotrophs - organic compounds from CO2
     • use range of different energy sources
       • so live in wide range of habitats
   • Problems
     • illnesses
     • antibiotic resistance
   • Structure
     • Plasmid DNA
     • chromosomal DNA
     • cell wall
     • flagellum
       • (sometimes)
     • cell membrane

2. YEAST

   • Reproduction
     • asexual budding
   • Structure
     • food storage granules
     • cytoplasm
     • vacuole
     • cell membrane
     • nucleus
   • What are yeast?
     • type of fungus
     • 1500 species have been described
       • 1% of all fungal species
     • unicellular
       • some species with yeast forms may become multicellular
         • through the formation of a string of connected budding cells
     • typically measure 3-4 µm in diametre
       • some reach up to 40 µm
   • How can optimum growth be maintained?
     • food present
       • (glucose)
     • temperature
       • growth doubles with every 10°C reached
         • until optimum temp.
     • optimum pH
     • remove waste products

3. VIRUSES

   • Reproduction
     • 1. virus attaches to a specific host cell
       • 2. genetic material injected into host cell, host cell stops own activities & starts making new components for new viruses
         • 3. new viruses made inside cytoplasm of host cell, using material inside host cell & genetic material from virus
           • 4. cell splits open allowing viruses to leave but killing host cell
   • Structure
     • strand of nucleic acid
       • DNA or RNA
     • protective protein coat
       • capsid
     • tail (sometimes)
     • lipid membrane (sometimes)
   • What are viruses?
     • 0.1µm in size
     • no metabolic activity
     • has to take over host cell to reproduce
   • disease
     • host cells make proteins for the virus
       • protective protein coat (capsid)
     • examples:
       • ebola
       • influenza
       • AIDs
     • viruses use materials from host cells
       • to make proteins
       • materials = amino acids