Test III- Ch. 7 Photosynthesis Flashcards
Photosynthesis definition
the metabolic pathway by which carbon dioxide is converted into glucose using light as energy.
Photosynthesis overall equation
6CO2+6H2O+photons—–> C6H12O6+6O2
2 Basic stages of Photosynthesis
- Light Reaction
2. Dark Reaction (Calvin cycle)
Light Reaction
- Takes lace on the membrane of the thylakoid
- Light must be available (only occurs during daylight)
Dark Reaction
(Calvin Cycle)
- Takes place in the stroma
- Uses the products of the light reaction (cannot function without light reaction)
Photon-
a “packet” of light energy, one quantum of light.
Photoelectric Effect
when a photon strikes an electron, this energizes the electron.
Pigment-
molecules that absorb light energy
primary pigment in plants = Chlorophyll
What is the net gain of ATP in photosynthesis?
None, all of the ATP created in photosynthesis is later used in the process to form glucose.
What is the source of all electrons in the light reaction?
H2O-these electrons replace the loss of electrons in the pigment that are lost in the photoelectric effect
Photosystems
Systems found on the thylakoid membrane.
- 2 Photosystems in the light reaction
- water splitting photosystem
- NADPH-producing photosystem
Water-splitting photosystem
- Photolysis: Splitting of the water molecule (releasing electrons)
- Electrons are used to run a proton pump
- ATP is synthesized by ATP synthase
NADPH-producing photosystem
- The role of NADP+ is the final electron acceptor for the electron produced by photolysis
- NADP+ is converted into NADPH
- NADPH carries the electrons to the Calvin Cycle
Photosynthetic unit
The unit where the light reaction takes place.
- Two photosystems (Water-Splitting and (NADPH-Producing)
- Two photosystems connected with electron transport chain
Calvin Cycle
- Cyclic reaction that occurs in the stroma
- CO2 is fixed into sugar molecules using:
- Energy from ATP, and:
- Electrons from NADPH
