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