Upload
melvin-henderson
View
219
Download
4
Tags:
Embed Size (px)
Citation preview
5- Microbial Metabolism
See Table 5.2 for some cofactors
(protein)
(organic)
What catalysts (eg: enzymes) do
(Enzyme is NOT used up)
How do enzymes work?
optimum optimum
competitive inhibition
Non-competitive inhibition
Some older enzyme names don’t follow the modern rules: trypsin, lysozyme, etc.
In many biological redox reactions: electrons are passed on as part of H atoms
Substrate-level phosphorylation
Oxidative- or Photo-phosphorylation
Catabolism
(= degradation)
aerobic
Glycolysis = Embden-Meyerhoff pathway
(see also appendix A)
G3P
Glycolysis (cont.)
2
2
2
2
2
Pentose-phosphate pathway
can use glucose
makes & uses pentoses & other useful substrates for biosynthesis
produces 2 NADPH/ glucose
& 1 ATP (through glycolysis)
(see also App. A-4)
Entner-Doudoroff pathway
uses glucose
produces 1 ATP & 1 NADPH & 1 NADH/glucose
in prokaryotes only
(see also App. A-5)
mitochondria
cytoplasm
Transition/preparatory step/reaction
In mitochondrial matrix
Kreb’s cycle
Citric Acid cycle
TCA cycle
(see also App. A-6)
oxidative -> ETC
phosphorylation -> chemiosmosis
energy
(Eukaryotic about the same)
Anaerobic Respiration: different final electron acceptor
acceptor product
nitrate (NO3-) -> nitrite (NO2
-)
-> nitrous oxide (N2O)
-> nitrogen gas (N2)
(eg: Pseudomonas, Bacillus)
sulfate (SO42-) -> hydrogen sulfide (H2S)
(eg: Desulfovibrio)
carbonate (CO3-) -> methane (CH4)
(eg: Methanogenium)
Some kinds of fermentation
Other kinds of catabolism
Anabolism (= biosynthesis)
Halobacterium
Photosynthesis
group PS pigments(s) 1) purple S bacteriochlorophylls a or b 2) purple non-S bacteriochlorophylls a or b---------------------------------------------------------- 3) green S bacteriochlorophylls a + c,
d, or e 4) green non-S bacteriochlorophylls a + c---------------------------------------------------------- 5) heliobacteria bacteriochlorophyll g---------------------------------------------------------- 6) Halobacterium bacteriorhodopsin---------------------------------------------------------- 7) cyanobacteria chlorophyll a + phycobilins---------------------------------------------------------- 8) PS-protists chlorophyll a + various 9) almost all chlorophyll a + b land plants
Chloroplast anatomy & the 2 sets of reactions
Overall:
6 CO2 + 12 H2O
in the presence of lightlight and chlorophyll a yields
C6H12O6 + 6 O2 + 6 H2O
LightLight Dependent Reactions:
12 H2O + 12 NADP+ + 18 ADP + 18 phosphates
with lightlight and chlorophyll a yields
6 O2 + 12 NADPH + 18 ATP
Light Independent Reactions:
12 NADPH + 18 ATP + 6 CO2
yields
C6H12O6 (glucose) + 12 NADP+ + 18 ADP + 18 phosphates + 6 H2O
Light Dependent Reactions
In eukaryotic chloroplasts & cyanobacteria there are 2 kinds of photosystems: I & II
Light Independent Reactions
12 NADPH + 18 ATP + 6 CO2 yields
C6H12O6 (glucose) + 12 NADP+ + 18 ADP
+ 18 phosphates + 6 H2O
(see also Appendix A-7)
In the stroma
Rubisco
Carbon fixation = making sugars
Chemosynthesis:
Using the energy from inorganic chemicals to put together CO2 into sugars
Only some prokaryotes can do
Is done where there is no light but can be done where there is light
Alternative to photosynthesis
eg: hydrogen bacteria, iron bacteria
Other biosyntheses: polysaccharides
Metabolism is
1) integrated and
2) many pathways, not all, are amphibolic
To see more:
http://www.manet.uiuc.edu/pathways.php
http://www.sigmaaldrich.com/etc/medialib/docs/Sigma-Aldrich/General_Information/metabolicpathways_updated_02_07.Par.0001.File.tmp/metabolic_pathways_poster.pdf
http://www.expasy.ch/cgi-bin/show_thumbnails.pl
http://www.genome.jp/kegg/pathway.html