Transcript Mini-lesson on prokaryotic and eukaryotic cells

Mini-lesson on prokaryotic and
eukaryotic cells
What the words mean
Prokaryotes
• Pro = before
• Karyose = kernel, which
represents the nucleus
• So prokaryotes occurred
before cells with a nucleus
Eukaryotes
• Eu = true
• Karyose = kernel, the
nucleus
• So eukaryotes are the cells
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
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Prokaryotic cell
DNA- circular, has no ends
Bacteria
Nucleoid – not a real
structure, just a word to
describe the inside of the
cell where the nuclear
material sits
Tiny cells- tough to see on
400x
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•
Eukaryotic cell
DNA- linear, has ends
Found in animals, plants,
and fungi (yeast)
True membrane bound
nucleus surrounding
chromosomes
Larger cells- could be seen
on 400x
More similarities and differences
Prokaryotes
• Ribosomes are simple
• No membrane bound
organelles
• Believed to be what led to
chloroplasts and
mitochondria (see next
slide)
Eukaryotes
• Ribosomes are complex
• Membrane bound
organelles
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…)