Plant respiration - chapter 11

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Plant respiration - chapter 11 The oxidation of
sugars to produce usable energy (ATP), reductant
(NADH), and carbon skeletons for
biosynthesis. C12H22O11 12O2 --gt 12 CO2 11
H2O 60 ADP 60 Pi --gt 60 ATP 60 H2O Where
does it occur? In the mitochondria of living
cells, both photosynthetic and
non-photosynthetic What are the major steps? 1)
Glycolysis 2) citric acid cycle 3) electron
transport/oxidative phosphorylation
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Fig. 11.1
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The mitochondrion
Fig. 11.5
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Glycolysis - conversion of carbohydrates
into pyruvate (organic acid) producing some ATP
and NADH. Can happen in presence or absence of
O2 If O2, then pyruvate converted to acetyl CoA
and into the citric acid cycle. If no O2,then
fermentation occurs, pyruvate is reduced to
lactic acid and/or ethanol.
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In aerobic conditions, pyruvate from glycolysis
is converted to acetyl CoA, which enters the
citric acid cycle where most of the NADH is
produced.
Fig. 11.6
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As in the chloroplast, a double membrane system
allows formation of an internal pH gradient
(p.m.f.) that is used for ATP production.
Fig. 11.10
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Mitochondrial electron transport oxidizes
NAD(P)H, and generates a p.m.f. that is used to
produce ATP. O2 is consumed as it acts as the
terminal electron acceptor. This production of
ATP is called oxidative phosphorylation
Fig. 11.8
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What about those carbon skeletons?
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The relationship of respiratory intermediates to
other plant biosynthetic pathways.
Fig. 11.13
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Respiration and plant carbon balance
Plant growth ?mass/?t ?C/?t ?C C gain in
photosynthesis - C loss in respiration ?C
photosynthesis - shoot respiration - root
respiration Respiration for growth and
maintenance. Growth respiration is for the
construction of new tissues, and is associated
with increase in mass. Maintenance is for solute
gradients, ion uptake, rebuilding of degraded
compounds, etc.
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Questions about plant respiration How does ATP
formation differ in mitochondria and
chloroplasts? What are their similarities? How
might soil flooding affect ATP production of root
cells? What might be the function of the
alternative oxidase? How does the spadix of a
skunk cabbage get so warm?