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Comparing Cell Sizes
Mycoplasma 0.3-0.8 µm
E. coli 1x2 µm
Cyanobacteria 10 µm diam
Plant Cell 30x75 µm
Obviously eukaryotic
Nucleus present
Mitochondrion  Bacterium
Chloroplast  Cyanobacterium
Endosymbiosis: Eukaryotes are Chimeras!
Cyanobacteria carry out photosynthesis with chlorophyll bound
to proteins in membranes infolding from the cell membrane.
Photosynthetic
Membranes
(thylakoids)
Figure 7-5 Page 122
This is an artificially-colored micrograph from
transmission electron microscopy (TEM)
Cyanobacterial Vegetative Cell:
mesosome
ETS
reactions
Photosynthesis
Respiration
cell wall
cell membrane
cyanophycean starch
gas
vacuole
thylakoids
light
(ETS)reacti
ons 70S
ribosome
cyanophycin
lipid droplet
polyphosphate granule
nucleoid
cytosol
polyhedral body
Calvin cycle
http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/CBDivideTEM.jpg
RuBisCO
sugar synthesis
light
glycolysis CO2 + H2O
CO2 + H2O + energy
O2 + CH2O O2 + CH2O
chlorophyll
Kreb’s cycle
An artificially colored TEM of a cyanobacterium.
Thylakoids contain chlorophyll a (green)
Metabolism?
Association?
Shape?
http://genome.jgi-psf.org/anava/anava.jpg
In dyed TEM image:
In a light microscope image:
Thylakoids were dyed green to show the
location of bacteriochlorophyll for the light
reactions…
Thylakoids are too fine to be visible, so the
green color appears throughout cytosol but
with the nucleoid region lighter in color. The
DNA displaces some of the naturally darkgreen thylakoids.
nucleoid
http://www.jgi.doe.gov/JGI_microbial/images/microbes2003/anava.jpg
http://www.bio.utexas.edu/research/utex/photogallery/Images/A
nabaena_cylindrica_629.jpg
Anabaena --a cyanobacterium w/ division of labor
Akinete
(hypnospore)
Heterocyst (N2 fixation)
http://www.ac-rennes.fr/pedagogie/svt/photo/microalg/anabaena.jpg
Cyanobacterial Heterocyst (N2 fixation)
cell wall
O2 block
cell membrane
nucleoid
mesosome
ETS for O2
reduction
cytosol
pore in wall
fuel input for
respiration
Nitrogenase
reduces N2
(requires
anaerobic
conditions)
http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/Heterocyst.jpg
Cyanobacterial Akinete (hypnospore)
cell wall
cell membrane
cyanophycean starch
polyhedral body
lipid droplet
polyphosphate granule
vacuole
cyanophycin
thylakoids
nucleoid
http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/AkineteEMBlue400.jpg
Germinating akinetes (producing vegetative filaments)
http://www-cyanosite.bio.purdue.edu/images/lgimages/oreg4.jpg