Carbon Cycles through Organisms in Respiration

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Carbon Cycles through Organisms in Respiration
autotrophes
heterotrophes
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All Cells Respire
Plants dont do photosynthesis FOR
animals They metabolize/use the sugars
themselves!
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Respiration Transforms Energy
Anaerobically (without O2)
4 ATP
Aerobically
38 ATP
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Reaction Energetics
Catabolic breaking down molecules Exergonic
releasing energy Redox transferring e-
Enzyme facilitated
from glucose to oxygen
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Glycolysis sugar break apart
10 step biochemical pathway Occurs in
cytoplasm (cytosol) of all organisms
Reactant 6 C glucose 2 ATP
Product two 3C pyruvate 4 ATP 2 NADH
e-
e-
NADH?
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Key Events in Glycolysis phosphate transfers

• Phosphate transfer from 2 ATP destabilizes
  glucose, starting the metabolic
  pathway

1 glucose C-C-C-C-C-C
P-C-C-C-C-C-C-P
.. Ultimately phosphate is transferred from G3P
to ADP forming 4 ATP
2 P-C-C-C
2 NAD
G3P(PGAL)
e-
e-
substrate-level phosphorylation
2 NADH
PYRUVATE
NAD?
http//highered.mcgraw-hill.com/sites/0072507470/s
tudent_view0/chapter25/animation__how_glycolysis_w
orks.html
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Energy Transfer via Electron Transfer Redox

• Break bonds of fuels (i.e. glucose) means
  electrons and energy are moved from one molecule
  to another

H H e-
Electrons move as part of a H atom
Oxidation losing H, e-
Reduction gaining H
Moving e- from glucose -gt final acceptor (O2,
lactate, ethanol) doesnt happen in one step
need intermediate e- carriers, like NAD
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Electron Transfer Molecules
Nicotinamide Adenine Dinucleotide
a coenzyme molecule (coenzyme organic) 1
H and 2 e- (or 1H, 1e-) transferred from glucose
to NAD, creating NADH
NAD 2H ? NADH H
the remaining H (proton) is free in the
cytosol
http//highered.mcgraw-hill.com/sites/0072507470/s
tudent_view0/chapter25/animation__how_the_nad__wor
ks.html
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Start here
Got fructose? Enter pathway here
Invest 2 ATP
PGAL/G3P produced by moving e- to NAD
e-
e-
Substrate-level phosphorylation of ADP -gt ATP
2 NADH
2 more Pi
Product!
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Pyruvate options
Anaerobic options
EVERY ORGANISM
E. coli C. botulinum YEAST BACTERIA
Staph spp
ALL EUKARYOTIC KINGDOMS
facultative anaerobes use O2 if present, but can
grow without obligate anaerobes no O2 tolerance
ANIMAL
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Anaerobic Resp v1 Fermentation 3
C Pyruvate acetlyaldehyde CO2
2 C ethanol
Reduce pyruvate to ethanol to recycle NAD
2
2
2
2
Beer is carbonated!
net
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Anaerobic Resp v1 Fermentation
Ethanol is toxic to yeast at about 12 limiting
the alcohol content of naturally fermented
products
some bacteria yeast
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Fermentation v2 Lactate
3 C Pyruvate 3 C lactate (to
lactic acid)
Reduce pyruvate to lactate to recycle NAD
2
2
2
2
(No CO2)
net
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Fermentation v2 Lactate