1. Prokaryotes Stephen Taylor i-Biology.net
Image: Hospital-associated MRSA by NIAID on Flickr

2. Prokaryotes “Before nucleus:” evolutionary precursors to eukaryotes.
Escherichia coli (E. coli)

3. Prokaryotic Cell Parts
mesosome
cell wall
plasma membrane
pili
cytoplasm
nucleoid
ribosomes
flagella
Prokaryotic cell parts are not generally membrane-bound, so we don’t refer to them as organelles.
Cell structures animation:

4. Prokaryotic Cell Parts
mesosome
cell wall: protective protein-based coating (Gram + / Gram -)
plasma membrane: selectively permeable, controls entry & exit of materials to and from the cell.
pili: attach to other bacteria for DNA transfer
cytoplasm: contains enzymes for metabolic reactions
nucleoid: closed-loop of bacterial DNA in a condensed area
ribosomes: protein synthesis (transcription & translation)
flagella: whiplash-like motion causes movement
Cell structures animation:

5. Prokaryotic Cell Parts
mesosomes
These don’t really exist naturally as bacterial cell parts, and could be an example of a paradigm shift in thinking.
They were observed in some electron micrographs and thought to be in-folds of membrane used for division, respiration or making cell walls…
… turns out they are an
artifact of the
preparation method
for some electron
microscope images.
Cell structures animation:

6. Past-paper question: E. coli TEM image
Identify these structures: I.
II.
III.
IV.
Calculate the magnification of the image.
Image from IB Biology QuestionBank CDRom – get a copy here:

7. Past-paper question: E. coli TEM image
Identify these structures:
I. Plasma membrane
II. Cell wall / pili
III. Nucleoid
IV. Cytoplasm / ribosomes
Calculate the magnification of the image. 1. Measure the scale bar in mm.
2. Multiply x 1000 to convert to μm.
That is the magnification.
How long is the bacterium?
Image from IB Biology QuestionBank CDRom – get a copy here:

8. PROKARYOTES E P R O D U C
through
binary fission
two-parts
splitting

9. binary fission PROKARYOTES E P R O D U C through
The closed-loop DNA of the bacterium makes copies through semi-conservative DNA replication.
New plasmids are pulled to opposing poles by the spindle fibres.
The bacterium divides in two.

11. How dirty is your phone? http://www.youtube.com/watch?v=4lmwbBzClAc

12. Prokaryotes divide by binary fission.
Life cycle of E. coli from:

17. He’d contracted a porkaryote.
A man got sick from E. coli after eating old sausages.
He’d contracted a porkaryote.
Photo: Sausages by Paul Hickman on Flickr (CC)

18. For more resources & links.
Please consider a donation to charity via Biology4Good.
Click here for more information about Biology4Good charity donations.
This is a Creative Commons presentation. It may be linked and embedded but not sold or re-hosted.