the use of solar energy to drive the anabolic pathways that produce the building blocks of life

the conversion of light energy to chemical energy and its subsequent use in synthesizing organic molecules

organisms that acquire energy from sunlight but depend on organic sources of reduced carbon

ex: halobacteria

organisms that use solar energy to synthesize energy-rich molecules from simple inorganic starting materials such as carbon dioxide and water

ex: plants, algae, bacteria

replenish reduced carbon in the biosphere and provide the oxygen in the atmosphere used by aerobic organisms to oxidize these reduced compounds for energy

 a process in which light is captured by chlorophyll molecules and converted to chemical energy in the form of ATP and NADPH

ATP and NADPH provide energy and reducing power for the carbon fixation reactions (calvin cycle)

a process in which fully oxidized carbon atoms from carbon dioxide are fixed (reduced and covalently joined), forming carbohydrates

take place in the chloroplast of the eukaryotic phototrophs

light energy from the sun is captured by a variety of green pigment molecules known as  ______.

light absorption by this molecule excites one of its electrons, which is then ejected from the molecule and flows energetically downhill through an electron transport system (ETS)

the primary energy-transduction pigment that channels solar energy into the biosphere

plants, algae, and cyanobacteria

water is the electron donor, and light energy absorbed by chlorophyll powers the movement of two electrons from water to NADP⁺ , which is reduced to NADPH

green and purple photosynthetic bacteria

compounds such as sulfide, thiosulfate, or succinate---> serve as electron donors, then...

oxidized forms of these compounds are released

the organelle responsible for most of the events of photosynthesis in eukaryotic phototrophs

found in most plants, but not all

any of several different types of plant cytoplasmic organelles derived from protoplastids

chloroplasts, amyloplasts, chromoplasts, proteinplasts, elaioplasts

the structure of this organelle is comprised of an outer membrane and an inner membrane often separated by a narrow intermembrane space.

the inner membrane encloses the stroma, a gel like matrix teeming with enzymes for carbon, nitrogen, and sulfur reduction and assimilation

the outer membrane contains transmembrane proteins called porins that permit the passage of solutes

a third membrane system inside the chloroplast that creates an internal compartment

saclike structures suspended in the stroma

arranged in stacks called grana (interconnected by a network of longer thylakoids called stroma thylakoids)

grana and stroma thylakoids enclose a single continuous compartment called the thylakoid lumen

the first stage of photosynthetic energy transduction in which  light energy is captured from the sun

light has both wave-like and particle-like properties

light behaves as a stream of discrete particles called photons, each photon carrying a quantum of energy

mechanism whereby the excitation of energy of a photoexcited molecule is transferred to an electron in an adjacent molecule, exciting that electron to a high-energy orbital

important means of passing energy from one pigment molecule to another in photosynthetic energy transduction

absorb photons that cannot be captured by chlorophyll and then transfer the energy of these photons to a chlorophyll molecule by resonance energy transfer

2 types: carotenoids and phycobilins

variations in the amounts and properties of _____ often reflect a phototroph's adaptation to a specific environment

collects light energy

does not contain a reaction center. instead passes the collected energy to a nearby photosystem by resonance energy transfer

photosystem containing a pair of chlorophyll molecules (P700) that absorbs red light

light of this wavelength can excite electrons derived from plastocyanin to an energy level that allows them to reduce ferredoxin, from which the electrons are then used to reduce NADP+ to NADPH

photosystem containing a pair of chlorophyll molecules (P680) that absorb red light

light of this wavelength can excite electrons donated by water to an energy level that allows them to reduce plastoquinone

in the reaction center of each photosystem is a distinctive ______ of chlorophyll a molecules that have the electrons that will be photoexcited following photon absorption

designated P680 for PSII and P700 for PSI to reflect their specific absorption maximum

the photosystems are somewhat mobile in the membrane and thus able to move to allow the cell to adapt to changing conditions of light quantity (brightness) and quality (wavelength)

the second stage of photosynthetic energy transduction uses a series of electron carriers to transport excited electrons from chlorophyll to the coenzyme _____, forming NADPH

this process is known as photoreduction and involves a chloroplast electron transport system

noncyclic electron flow in oxygenic phototrophs

--->

continuous, unidirectional flow of electrons from water to NADP during the energy transduction reactions of photosynthesis, with light providing the energy that drives the transfer

in plants and green algae, PSII is usually associated with _________, which contains about 250 chlorophyll and numerous carotenoid molecules

energy captured by this complex is funneled to the reaction center by resonance energy transfer

P680 becomes a better electron donor

fully reduced form of plastoquinone, invovled in the light requiring reactions of photosynthesis

present in the lipid phase of the photosynthetic membrane, where it transfers electrons to the cytochrome b₆/f complex

enzyme that catalyzes the carbon dioxide-capturing step of the calvin cycle

forms 2 molecules of 3-phosphoglycerate

two-carbon compound produced by the oxygenase activity of rubisco

it cannot be metabolized during the next step of the calvin cycle and thus, the production of _____ decreases photosynthetic efficiency

light-dependent pathway that decreases the efficiency of photosynthesis by oxidizing reduced carbon compounds without capturing the released energy