B6a Summary

B6a Summary

BACTERIA
1. What are bacteria?
  1. unicellular organsims
  2. cells are just a few micrometres long
    1. I µm = 0.001mm
      1. micrometre = µm
  3. plant & animal cells are 10X bigger
2. Classification of Bacteria
  1. Rod
  2. Curved Rod
  3. Spherical
  4. Spiral
3. Handling Bacteria
  1. aseptic techniques
    1. wear gloves
      1. or wash hands before and after
    2. disinfect working areas
    3. sterilise all equipment
    4. never leave lid off the containers
4. Bacterial Reproduction
  1. Binary Fission
  2. in ideal conditions bacteria reproduce every 20 minutes
    1. after 4 hours you could have 4096 bacteria
  3. consequences on health & food storage
    1. will reproduce if left in warm conditions
    2. put food in fridge
      1. colder temp. slows enzyme activity and so slower reproduction
5. How do they feed?
  1. consumption of organic nutrients
    1. carbohydrates
    2. proteins
  2. some make own food
    1. photosynthetic bacteria
    2. hydrogen sulfide/ammonia to provide energy
      1. to make food
      2. e.g. chemoautotrophs - organic compounds from CO2
  3. use range of different energy sources
    1. so live in wide range of habitats
6. Problems
  1. illnesses
  2. antibiotic resistance
7. Structure
  1. Plasmid DNA
  2. chromosomal DNA
  3. cell wall
  4. flagellum
    1. (sometimes)
  5. cell membrane
YEAST
1. Reproduction
  1. asexual budding
2. Structure
  1. food storage granules
  2. cytoplasm
  3. vacuole
  4. cell membrane
  5. nucleus
3. What are yeast?
  1. type of fungus
  2. 1500 species have been described
    1. 1% of all fungal species
  3. unicellular
    1. some species with yeast forms may become multicellular
      1. through the formation of a string of connected budding cells
  4. typically measure 3-4 µm in diametre
    1. some reach up to 40 µm
4. How can optimum growth be maintained?
  1. food present
    1. (glucose)
  2. temperature
    1. growth doubles with every 10°C reached
      1. until optimum temp.
  3. optimum pH
  4. remove waste products
VIRUSES
1. Reproduction
  1. 1. virus attaches to a specific host cell
    1. 2. genetic material injected into host cell, host cell stops own activities & starts making new components for new viruses
      1. 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
2. Structure
  1. strand of nucleic acid
    1. DNA or RNA
  2. protective protein coat
    1. capsid
  3. tail (sometimes)
  4. lipid membrane (sometimes)
3. What are viruses?
  1. 0.1µm in size
  2. no metabolic activity
  3. has to take over host cell to reproduce
4. disease
  1. host cells make proteins for the virus
    1. protective protein coat (capsid)
  2. examples:
    1. ebola
    2. influenza
    3. AIDs
  3. viruses use materials from host cells
    1. to make proteins
    2. materials = amino acids

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