Mini-lesson on prokaryotic and eukaryotic cells

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					Mini-lesson on prokaryotic and
        eukaryotic cells
           What the words mean
Prokaryotes                     Eukaryotes
• Pro = before                  • Eu = true
• Karyose = kernel, which       • Karyose = kernel, the
  represents the nucleus          nucleus
• So prokaryotes occurred       • So eukaryotes are the cells
  before cells with a nucleus     with a true nucleus
A prokaryotic cell
http://www.cod.edu/PEOPLE/FACULTY/FANCHER/ProkEuk.htm
Eukaryotic cell
http://www.cod.edu/PEOPLE/FACULTY/FANCHER/ProkEuk.htm
        Similarities and Differences
          Prokaryotic cell                 Eukaryotic cell
•   DNA- circular, has no ends    •   DNA- linear, has ends
•   Bacteria                      •   Found in animals, plants,
•   Nucleoid – not a real             and fungi (yeast)
    structure, just a word to     •   True membrane bound
    describe the inside of the        nucleus surrounding
    cell where the nuclear            chromosomes
    material sits                 •   Larger cells- could be seen
•   Tiny cells- tough to see on       on 400x
    400x
  More similarities and differences
         Prokaryotes                   Eukaryotes
• Ribosomes are simple         • Ribosomes are complex
• No membrane bound            • Membrane bound
  organelles                     organelles
• Believed to be what led to
  chloroplasts and
  mitochondria (see next
  slide)
   Chloroplasts and mitochondria
• Evidence suggests that chloroplasts and
  mitochondria were once bacteria that
  developed a symbiotic relationship with cells
  that have a nucleus
• Chloroplasts and mitochondria have their own
  circular DNA that is not a part of the host’s
  genome.
• Yes plants have both chloroplasts and
  mitochondria.
     What happened with the gram
              staining?
               Staining Bacteria

• Gram stains work because of their membrane
  structure
• Methylene blue works, but the buttermilk was
  too messy to really be able to see all of the
  teeny tiny dots (sorry)
                Staining Yeast
• Gram stains won’t work because of their
  membrane structure
• Ethanol shrunk the cells in the gram stain so
  the cells looked like tiny dots, if you could find
  them
• Methylene blue works great
• All of your yeast should have been killed from
  the heat and therefore were blue
         If the world was perfect…
               (which it is not, by the way)

• The bacteria would have come out gram positive
  because they were Streptococcus
• You would have been able to see teeny tiny little
  balls on the slide
• You did NOTHING WRONG.
• The destaining step needs to be explained better
  in the protocol.
• Next year we’ll try culturing the cells before
  making slides of them. Sorry for the frustration.
  (But this is how science is sometimes…)

				
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posted:9/24/2012
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