CB1 - Key Concepts in Biology

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1a - Microscopes

  • invented in 1500s and have 2 lenses
  • Robert Hooke used them to discover cells using x30 magnification
  • in 1675 eye pieces were improved by Leeuwenhoek
  • resolution is smallest distance between 2 points before turns into 1 point
  • light microscope can magnify uptp x1500 with resolution of 0.000 1mm
  • electron microscope (1930s) builds up image by firing electrons. x2 000 000 magnification and 0.000 000 2mm resolution
  • magnification = eye piece x eye lense

mm  <- x1000 micrometer   <- x1000 nanometer  <- x1000 picometer

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1b - Plant and Animal cells

  • 1828 Robert Brown examined cells in surface of leaf and found nucleus
  • cells that have a nucleus are eukaryotic 
  • nucleus controls cell activities, contains DNA with chromosomes, large in white blood cellls
  • cytoplasm -> contains ribosomes that create protein, jelly like, where most activities happen
  • Mitochondria -> jelly bean shaped, where aerobic respiration takes place
  • cell membrane -> very thin, controls what enters and leaves cell
  • cell wall -> made of cellulose amd protects cell
  • chloroplast -> contains chlorophyll, traps energy from sun for photosynthesis
  • vacuole -> contains sap,helps keep cell rigid
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