Oxygen uptake: Dark respiration: in mitochondria water production, CO 2 release ATP production inhibitor: KCN Photorespiration: in chloroplast, peroxisome, mitochondria oxygen cycle, CO 2 release ATP consume inhibitor: DCMU decreased photosynthetic efficiency Alternative respiration: Mehler reaction (1951): in chloroplast (PS1), O 2 → H 2 O 2 No CO 2 release promote photosynthetic efficiency
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Oxygen uptake: Dark respiration : in mitochondria water production, CO 2 release ATP production inhibitor: KCN Photorespiration : in chloroplast, peroxisome,
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Oxygen uptake:
Dark respiration: in mitochondria
water production, CO2 release
ATP production
inhibitor: KCN
Photorespiration: in chloroplast, peroxisome, mitochondria
oxygen cycle, CO2 release
ATP consume
inhibitor: DCMU
decreased photosynthetic efficiency
Alternative respiration:
Mehler reaction (1951): in chloroplast (PS1), O2 → H2O2
No CO2 release
promote photosynthetic efficiency
The dural function of water-water cycle:
1. scavenging active oxygen, then reinforce the CO2 assimilation
2. safe dissipation of excess photon energy
Mehler
lighting
P. 274 ~ 275
¤ Respiration rate
depends on the species and growth habit of the plant, the type and age of the specific
organ, and environmental variables, such as temperature, nutrient and water supply.
Whole plant:
on a fresh-weight basis: generally lower than animal’s rate
isolated plant mitochondria:
as fast as or faster than mammalian mitochondria
Plants respire roughly half of the daily photosynthetic yield
tropic plants: higher normal respiration (consumption of 70~80% daily PS gain)
younger vs. older trees (photosynthetic/nonphotosynthetic tissues)
lose 1/3 vs. 2/3 of their photosynthate as respiration
Photosynthesis rate (Max.) Photorespiration rate normal respiration rate
[chloroplast] [C, M, peroxisome] [mitochondria]
Different tissues and organs respire at different rates
Environmental factors alter respiration rate : P. 277 ~ 278
O2:
the Km for oxygen of cytochrome c oxidase is below 1 M
the oxygen concentration of aqueous solution is 250 M (21% O2 in air)
water saturation, flooded (diffusion limitation) [O2]
hydroponic culture: O2 supply
aerenchyma: intercellular air spaces from leaves to roots
pneumato(de)phores, trees that grow in mangrove, swamps
temperature:
T, respiration rate ( 0 to 30°C)
Q10, short-term; if long-term, acclimated [commercial Q10]
too low, decreased respiration rate, stimulated stored starch degradation
optimum storage temperature (7~9 °C for potato), too high or low