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Biology F211

microscopy
1. Staining
  1. most biological material is transparent
  2. simple stains include
    1. iodine solution
      1. this stains starch grains black and other structures yellow
    2. methylene blue
      1. this stains the nuclei blue
Cell membranes
1. the fluid mosaic model
2. made up of a phospholipid bilayer
3. also contains proteins
  1. some are used in faciliated diffusion across the membrane
    1. channel proteins
      1. forms a tunnel
      2. used for water-soluble molecules
      3. can be gated
    2. carrier proteins
      1. change shape to move molecules
      2. molecules will bind to the protein
4. transport across membranes
  1. active transport
    1. movement against the concentration gradient low-->high
    2. uses energy from ATP
    3. used to pump ions and molecules in and out of cells
    4. bulk transport
      1. exocytosis
        substances are packaged by the golgi
        they are then delivered to the surface by vesicles
        these fuse with the cell membrane and push out their contents
      2. endocytosis
        some cells take up large molecules- proteins and much larger solid objects like bacteria
        they do this by enclosing them inside vesicles or vacuoles formed by the cell surface membrane
  2. diffusion
    1. occurs passively
      1. no energy/ATP required
    2. moves down the concentration gradient
      1. high --> low
    3. molecules will be small and uncharged, to allow for easy passage through the bilayer
  3. osmosis
    1. special form of diffusion
      1. only occurs with water
  4. water potential
    1. the tendency for water to move from high-->low water potential
    2. pure water=o
      1. always a negative value
    3. measured in kPa
cell division & mitosis
1. stages
  1. 4-anaphase
    1. centrioles pull
      1. this contracts the spindle, pulling chromosomes apart
  2. 1- interphase
    1. majority of time in this stage
      1. around 22 hours in human cell
    2. protein synthesis occurs
    3. cytoplasm volume increases
    4. extra DNA/ organelles made
  3. 5-telophase
    1. spindle fibres have gone
    2. membranes reform
    3. chromatids are separate and now called chromosomes
    4. chromosomes unwind back into chromatin
  4. 3-metaphase
    1. no nuclear membrane
    2. centrioles are opposite
    3. microtubules form nuclear spindle
      1. chromosomes move to the spindle and attach by centrometre
  5. 2-prophase
    1. DNA and chromosomes are packaged
    2. chromosomes shorten and thicken
      1. makes it easier for chromosomes to move around
    3. nuclear envelope begins to break down
    4. centrioles move to poles
  6. 6-cytokinesis
    1. division between two new cells forms
      1. animals pinch inward
      2. plants form from middle
2. yeast budding
  1. mitotic division to produce clones
  2. a vesicle fuses out of the cell
    1. nuclei travels to this new bud, then splits
  3. it is normal mitosis until after telophase when this occurs
  4. form of asexual reproduction

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Biology F211

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	Created by Abbie Randall almost 12 years ago