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74 Cards in this Set

  • Front
  • Back


Survived on nutrients from the environment


Manufacture organic nutrients from CO2 and H2S

_________ of complex molecules from CO2 requires a large input of energy



Use energy from inorganic molecules


Use radiant energy to make organic molecules


Converts energy from sunlight into chemical energy stored in carbohydrates

Low energy electrons are removed from a _____ molecule


First photoautotrophs used ___ as electron source


Cyanobacteria used electrons from to produce _____ as a waste product


Photosynthesis in eukaryotes takes place in the __________



A cytoplasmic organelle.

Chloroplasts have a double _________


The outer membrane of chloroplast is ________ to large molecules


The inner membrane contains ________, __________, and _____________________

light-absorbing pigment

electron carriers

ATP-synthesizing enzymes

The inner membrane of a chloroplast is folded into ________ arranged in stacks called _______

flattened sacs (thylakoids)


Chloroplasts are self-replicating organelles containing their own ___


Thylakoid membranes contain a large percentage of glycolipids, which make the membrance highly fluid for ________________

Diffusion of proteins complexes

Photosynthesis is a redox reaction transferring an electron from ______ to _______

Water to Carbon Dioxide

Photosynthesis oxidizes ______ to ________

Water to Oxygen

Respiration reduces ______ to form ______

Oxygen to form water

Respiration removes high energy electrons from reduced organic substrates to form ____ and _____


Photosynthesis uses low energy electrons to form ___ and ______, which are then used to reduce CO2 to carbohydrate


Light-dependent reactions (light reactions)

Sunlight is absorbed, converting it into ATP and NADPH

Light-independent (dark reactions)

Use the energy stored in ATP and NADPH to produce carbohydrate

Absorption of photons by a molecule makes them go from _____ to ______

ground state to excited state

Energy in the photon depends on the __________________

wavelength of light

Molecules absorb specific _______________

wavelengths of light

Photosynthetic Pigments

Molecules that absorb light of particular wavelengths

Chlorophyll contains a ________________ that absorbs light and a ____________________ embedding it to the photosynthetic membrane

porphyrin ring

hydrophobic tail

The alternating single and double bonds along the porphyrin ring form a cloud making it a __________ system


Conjugated bond systems absorb energy of range of ___________


Besides chlorophyll, there are accessory pigments called __________



absorb light in the blue-green region of spectrum

Each Photosynthetic Unit contains

several hundred chlorophyll molecules

The reaction-center chlorophyll

transfers electrons to an electron acceptor

Pigments that do not participate directly in the conversion of light energy are responsible for light absorption called ________ pigments


Two large pigment-protein complexes called ___________ act in series to raise electrons from H20 to NADP+


Photosystems II (PSII)

Boosts electrons from below energy level of water to a midpoint

Photosystem I (PSI)

Boosts electrons to a level above NADP+

The reaction center of Photosystem II is referred to as ______


The reaction center of Photosystem I is referred to as ______


Electrons are transferred to a ____________________________

Primary electron acceptor

The flow of electrons from H20 to NADP+ is refereed to as the ____________

Z scheme

Photosystem II uses absorbed light energy to remove ________ and generate a _______________


proton gradient

Two proteins, D1 and D2, bind the P680 chlorophyll and perform reactions to ________________

oxidize H20

Light is harvested by a pigment-protein complex called __________________

light-harvesting complex II (LHCII)

Harvested energy is passed from LHCII to ___________________________ within PSII

inner-antenna molecules

Excited P680 transfers energy to an electron acceptor generating ______ and _______

P680+ and Pheo-

P680+ and Pheo- are transferred to opposite sides of the thylakoid membrane where Pheo- passes an electron to _________________

Plastiquinone (PQ)

Plastiquinone (PQ) passes the electron to __________, then moved to the ___________ of the membrane

Another PQ

stromal side

The Flow of Electron from Water to PSII

The redox potential of P680+ pulls electrons from water (photolysis)

Formation of O2 requires four electrons from H20

Four electrons required to form O2 are transferred in cycles through P680+ to four Mn ions and one Ca ion that form the oxygen-evolving complex

Protons produced in photolysis are retained in the thylakoid lumen

Oxygen produced is released as a waste product into the environment

From PSII to PSI

Production of O2 leads to formation of 2 molecules of PQH2

Reduced PQH2 then diffuses through thylakoid membrane and binds cyochrome b6f and releases protons the lumen of thylakoid

Electrons from cytochrome b6f are passed to another carrier plastocyanin

Plastocyanin transfers electrons to P700+

PSI Operations: The production of NADPH

The PSI consists of a reaction core center of 12–14 different polypeptides and a complex of protein-bound pigments called LHCI.
Photons harvested by antenna pigments in PSI (LHCI) oxidizes chlorophyll a, forming P700*.
Absorption of light leads to production of P700+ and Ao–.
Redox potential of P700+/Ao– reduces NADP.
The reduction of NADP+ to NADPH is catalyzed by ferredoxin-NADP+ reductase.
Some electrons passed to ferredoxin end up reducing nitrate, ammonia or sulfate to form other important biological molecules.

Photosynthetic Electron Transport

For every 8 photons absorbed:

2H20 + 2NADP+ => O2 + 2NADPH

Electron transport also produces a proton gradient across the thylakoid membrane

The machinery for ATP synthesis in a chloroplast is similar to that of ________________________

mitochondrial enzymes

The ATP synthase consists of a _____ and a ______

head (CF1)

base (CF0)

The CF1 heads project outward into the stroma, keeping with the orientation of the _________________

proton gradient

Protons move into the lumen through the CF0 base of the _______


The movement of protons during photo-synthesis does not create a significant change in the membrane potential since other ions are ______________________________

transported simultaneously

The movement of electrons during the formation of oxygen is called __________________________ because the ions move in a linear path

noncyclic photophosphorylation

Cyclic photophosphorylation is carried out by PSI __________ of PSII


C_3 plants

Plants that produce a 3 carbon intermediate as the first compound to be identified during carbon dioxide fixation

The condensation of RuBP and the splitting of the 6 carbon molecule are catalyzed by 1 enzyme:

Rubisco (ribulose biphosphate carboxlase)

Calvin Cycle

  • Carboxylation of RuBP to form PGA
  • Reduction of PGA to glyceraldhyde 3 phosphate (GAP) using NADPH and ATP from light reactions
  • Regeneration of RuBP

Carbohydrate Synthesis in C_3 plants

  • The GAP Molecules can be exported into the cytosol in exchange for phosphate ions and used to synthesize sucrose
  • Conversion of 6 molecules of CO2 to 1 6-carbon sugar molecules requires 12 molecules of NADPH and 18 molecules of ATP

Redox Control is light _______


Key enzymes of Calvin Cycle are only active when ________ and _________ are produced by photosynthesis


Some electrons used to reduce NADP+ are transferred to thioredoxin, which are accepted to ________________________________________

reduce disulfide bridges (-S-S-) in selected Calvin Cycle enzymes

In the _______, thioredoxin reduction ceases and enzymes go back to oxidized state and are inactivated



uptake of O2 and release of CO2

Glycolate produced during photorespiration is shuttled to the _________


Peroxisomal enzymes convert glycolate to glyoxylate and then glycine, resulting in the loss of ____


C4 pathway involves the production of ____________________________, which then combines with CO2 to produce 4-carbon compounds oxaloacetate

Phosphoenolpyruvate (PEP)

CAM plants

Carry out light reactions and CO2 fixation at different times of the day using the enzyme PEP carboxylase