Prokaryotes

For the IB Diploma Programme Biology Course.

1. Image: Hospital-associated MRSA by NIAID on Flickr http ://flic.kr/p/ a4RLq5 Stephen Taylor i-Biology.net Prokaryotes

2. Escherichia coli (E. coli) http://en.wikipedia.org/wiki/ Escherichia_coli Pro karyotes “ Before nucleus:” evolutionary precursors to eukaryotes.

3. Cell structures animation: http ://www.wiley.com/legacy/college/boyer/0470003790/animations/cell_structure/ cell_structure.swf cell wall plasma membrane pili ribosomes flagella mesosome cytoplasm nucleoid Prokaryotic Cell Parts Prokaryotic cell parts are not generally membrane-bound, so we don’t refer to them as organelles.

4. Cell structures animation: http ://www.wiley.com/legacy/college/boyer/0470003790/animations/cell_structure/ cell_structure.swf 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 ribosomes : protein synthesis (transcription & translation) flagella: whiplash-like motion causes movement mesosome cytoplasm: contains enzymes for metabolic reactions nucleoid : closed-loop of bacterial DNA in a condensed area Prokaryotic Cell Parts

5. Cell structures animation: http ://www.wiley.com/legacy/college/boyer/0470003790/animations/cell_structure/ cell_structure.swf mesosomes Prokaryotic Cell Parts 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. http://en.wikipedia.org/wiki/ Mesosome

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

7. Past-paper question: E. coli TEM image Image from IB Biology QuestionBank CDRom – get a copy here: https://store.ibo.org/ biology 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?

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

9. P R OKARYOTES E P R O D U C E through binary fission 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.

10. http://www.youtube.com/watch?v= gEwzDydciWc

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: http ://en.wikipedia.org/wiki/ Escherichia_coli

13. A man got sick from E. coli after eating old sausages. He’d contracted a pork aryote . Photo: Sausages by Paul Hickman on Flickr (CC) http://flic.kr/p/ bzcFSn

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