Homeostasis - metabolism

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Homeostasis - metabolism
Nutrition Mode Energy Source Carbon Source
Photoautotroph Light CO2
Chemoautotroph Inorganic chem CO2
Photoheterotroph Light Organic chem
Chemoheterotroph Organic chem Organic chem
All of these nutritional modes are found among
Bacteria! No other kingdom is as diverse in its
metabolic pathways.
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Photoautotrophs - photosynthesis

• Ancient pathway, but not universal
• Cyanobacteria, Algae, Plants
• light
• CO2 H2O ? O2 CH2O
• chlorophyll
• Purple-sulfur bacteria
• light
• CO2 H2S ? Ss CH2O
• chlorophyll

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http//www.plantmorphogenesis.bio.titech.ac.jp/ima
ges/Chloroplast20Photo.jpg
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http//faculty.uca.edu/johnc/Chloroplast_and_micr
obodies.jpg
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http//www.jgi.doe.gov/JGI_microbial/images/microb
es2003/anava.jpg
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Chemoautotrophs - N metabolism

• Cyanobacteria, Rhizobium - N2 fixation
• H ATP N2 ? NH4
• Nitrosomonas - nitrification
• CO2 NH4 ? NO2- CH2O
• Pseudomonas - denitrification
• CH2O NO3- ? N2 CO2 H2O

v
Which of these processes is demonstrating chemoaut
otrophism?
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http//soils.usda.gov/sqi/soil_quality/soil_biolog
y/images/Nods_on_beans_LR.jpg
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Photoheterotrophs - strange

• Rhodospirillum, Rhodomicrobium
• Light
• C2H4O2- H2O ? O2 CH2O

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http//www.acadweb.wwu.edu/courses/envr429-rm/Robi
n/images/envr429/1_rhodospirillum_600x.jpg
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Chemoheterotrophs - strange

• Escherichia coli and many others!
• CH2O O2 ? CO2 H2O
• Carbohydrate, etc. provides both
• the energy source
• and
• the carbon source

What is another chemoheterotrophic organism?Give
the complete Latin binomial!
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Plant mitochondrion
outer membrane inner membrane
cristae (mesosomes)
http//www.up.ac.za/academic/electron/mito1.htm
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Chemoheterotrophy

• Aerobic Respiration
• Glycolysis carbohydrate to pyruvate
• Citric Acid Cycle pyruvate to carbon dioxide
• Electron Transport Oxidative Phosphorylation
• CH2O O2 ? CO2 H2O
• Anaerobic Fermentation
• Glycolysis to pyruvate
• Fermentive step(s) to return NAD to glycolysis
• C6H12O6 ? C3H3O3- ? C2H5OH CO2
• C6H12O6 ? C3H3O3- ? H3CCHOHCOO-

Notice how fermentation can produce gas or
acids These are just a few of the fermentive
possibilities!