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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: Photosynthesis Cyanobacterial Vegetative Cell: Respiration cell wall mesosome ETS reactions cell membrane cyanophycean starch cyanophycin gas vacuole lipid droplet polyphosphate granule thylakoids light (ETS)reactions 70S ribosome nucleoid cytosol polyhedral body RuBisCO Calvin cycle sugar synthesis glycolysis Kreb’s cycle http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/CBDivideTEM.jpg light chlorophyll H2O O2 CO2 + + CH2O O2 + CH2O CO2 + H2O + energy

An artificially colored TEM of a cyanobacterium. Thylakoids contain chlorophyll a (green) Metabolism? Association? Shape? http://genome.jgi-psf.org/anava/anava.jpg

In a light microscope image: In dyed TEM image: Thylakoids were dyed green to show the location of bacteriochlorophyll for the light reactions… In a light microscope image: 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 dark-green thylakoids. nucleoid http://www.jgi.doe.gov/JGI_microbial/images/microbes2003/anava.jpg http://www.bio.utexas.edu/research/utex/photogallery/Images/Anabaena_cylindrica_629.jpg

Anabaena --a cyanobacterium w/ division of labor Vegetative Cells (Photosynthesis) 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 Nitrogenase reduces N2 (requires anaerobic conditions) pore in wall fuel input for respiration 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