Biology F211

Biology F211

1. microscopy

   • Staining
     • most biological material is transparent
     • simple stains include
       • iodine solution
         • this stains starch grains black and other structures yellow
       • methylene blue
         • this stains the nuclei blue

2. Cell membranes

   • the fluid mosaic model
   • made up of a phospholipid bilayer
   • also contains proteins
     • some are used in faciliated diffusion across the membrane
       • channel proteins
         • forms a tunnel
         • used for water-soluble molecules
         • can be gated
       • carrier proteins
         • change shape to move molecules
         • molecules will bind to the protein
   • transport across membranes
     • active transport
       • movement against the concentration gradient low-->high
       • uses energy from ATP
       • used to pump ions and molecules in and out of cells
       • bulk transport
         • 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
         • 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
     • diffusion
       • occurs passively
         • no energy/ATP required
       • moves down the concentration gradient
         • high --> low
       • molecules will be small and uncharged, to allow for easy passage through the bilayer
     • osmosis
       • special form of diffusion
         • only occurs with water
     • water potential
       • the tendency for water to move from high-->low water potential
       • pure water=o
         • always a negative value
       • measured in kPa

3. cell division & mitosis

   • stages
     • 4-anaphase
       • centrioles pull
         • this contracts the spindle, pulling chromosomes apart
     • 1- interphase
       • majority of time in this stage
         • around 22 hours in human cell
       • protein synthesis occurs
       • cytoplasm volume increases
       • extra DNA/ organelles made
     • 5-telophase
       • spindle fibres have gone
       • membranes reform
       • chromatids are separate and now called chromosomes
       • chromosomes unwind back into chromatin
     • 3-metaphase
       • no nuclear membrane
       • centrioles are opposite
       • microtubules form nuclear spindle
         • chromosomes move to the spindle and attach by centrometre
     • 2-prophase
       • DNA and chromosomes are packaged
       • chromosomes shorten and thicken
         • makes it easier for chromosomes to move around
       • nuclear envelope begins to break down
       • centrioles move to poles
     • 6-cytokinesis
       • division between two new cells forms
         • animals pinch inward
         • plants form from middle
   • yeast budding
     • mitotic division to produce clones
     • a vesicle fuses out of the cell
       • nuclei travels to this new bud, then splits
     • it is normal mitosis until after telophase when this occurs
     • form of asexual reproduction

Images and files in the map