Photosynthesis- Calvin Cycle
What does rubisco adds into the calvin cycle during photorespiration?
*O2* INSTEAD of CO2
What does the closing of a stoma cause? - -
- reduce access to CO2 - O2 build up
What do CAM plants do
Open their stomata at night, incorporating CO2 into organic acids
*similar to citric acid cycle The calvin cycle regenerates its starting materials after
molecules enter and leaves the cycle
the calvin cycle build sugar from smaller molecules by - -
- using ATP -reducing the power of electrons carried by NADPH
The 3 Phases Of The Calvin Cycle 1. 2. 3.
1. Carbon Fixation (catalyzed by rubisco) 2. Reduction (using electrons of splitting of h20 in light cycle and carried by NADP) 3. Regenerates CO2 acceptor (RuBP)
For net synthesis of 1 G3P, the cycle must occur _____, which is fixing(making) 3 molecules of *CO2*
3 times!
Photorespiration is a problem in many plants because on a hot, dry day it can drain ____% of ___ fixed by *calvin cycle*
50% carbon.
Carbon enters the Calvin Cycle as ____ and leaves a sugar named _____
CO2 leaves a sugar named Glyceraldehyde 3-Phosphate (G3P)
Problem for plants: which leads to:
Dehydration - requiring trade-offs with other metabolic processes, esp. photosynthesis
The Calvin cycle uses ____ and ______ to convert _____ to sugar
ATP & NADH CO2 (carbon dioxide)
what kind of cells is co2 incorporated to by C4 plants to 4 carbon compounds?
Mesophyll cells
Photorespiration consumes 1._____ & 2.____ fuel. releases 1. ___ without producing 2.____ or 3.____
O2, and organic. CO2, ATP or Sugar.
what does this step (mesophyll cells) requires the enzyme ______ ____
PEP carboxlyase
What does this "wasteful process" of rubisco binded with o2 catalytic efficient called:
Photorespiration
some plants (including ____) use ____ acid metabolism (CAM) to fix carbon
Succluents Crassulacean
CAM plants (Time)
another way
Alternative mechanisms of *carbon fixation* is evolved in ____ and _____ climates
hot and arid
Photorespiration is known as a "Evolutionary Relic* because rubisco first evolved when the atmosphere had less ____ and more ____
less O2 more CO2
photorespiration- limits: that build up in the absence of the
limits: damaging products of *light reactions* - that build up: in absence of calvin cycle
What happens to a plant's stomata during hot & dry days? - what does this limit? -
close their stomata, to save water. but it limits photosynthesis.
so in cam Stoma ____during the day CO2 is released from organic acids and uses in the calvin cycle
closes -
what do the bundle-shealth cells release?
co2!! for the calvin cycle
The calvin cycle builds_____ from _____
sugar from smallermolecules
In plants (c3 plants) initial fixation of *CO2 Via Rubisco* forms _____ ___ compound
three-carbon
Rubisco can bind _____ with catalytic efficiency
Rubisco can bind with O2
Where are these 4 carbon compounds are exported to?
bundle-sheath cells
C4 plants: *change time*** how do C4 plants minimize the cost of photorespiration?
by incorporating CO2 into four-carbon compounds in *mesophyll cells*
In the first phase of calvin cycle uses which enzyme to catalyze it?
rubisco
