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organisms that use light as a source of energy to synthesize organic substances.


the major sites of photosynthesis in most plants


green pigment locateed within the chloroplasts.


tissue in the interior of the leaf. where most chloroplasts are found.


microscopic pores in the leaf which lets co2 in and o2 out.


part of leaves that functions to export sugar to roots and other nonphotosynthetic parts of the plant.


stack of thylakoids


dense fluid within the chloroplast. site of dark reaction

intermembrane space

area between the two membranes of a chloroplast


flattened membranes in the chloroplast which is where the light reaction takes place.

6CO2 + 12H2O + light energy -> C6H12O6 + O2 + 6H2O

actual equation of photosynthesis.


from which reactant is the O2 product derived from? (in photosynthesis equation)

light reaction

part of photosynthesis that involves electromagnetic energy (visible light). ATP and NADP are produced. takes place in the thylakoid membrane.


molecules that absorb, reflect, or transmit light


machine that measures transmission/absorbance of light through a substance.


a cluster of pigments embedded into a thylakoid membrane

oxidizing agent

takes electrons and becomes reducted

reducing agent

gives electrons and becomes oxidized.


substance that supplies constant electron supply for the light reaction of photosynthesis.

noncyclic photophosphorolation

a term that referrs to how e- are lost in NADPH in the complete light reaction.

cyclic photophosphorolation

a term that refers to the negative feedback inhibitor of photosystem I that is needed when NADPH reductase needs to be inhibited


A reaction taking place in the thylakoid membranes of a chloroplast during light-dependant reactions where two molecules of water are split to form oxygen, hydrogen ions, and electrons


process of adding a phosphate group

carbon fixation

the initial incorporation of carbon into organic compounds

calvin cycle

carbon fixation process (aka dark reaction) in photosynthesis. forms sugar/other organic compounds

absorption spectrum

a graph plotting a pigment light light absorption

action spectrum

a profile of the relative performance of the different wavelengths in photosynthesis.

chlorophyll a

only pigment that can participate directly in the light reactions


hydrocarbons/ accesory pigments that broaden the spectrum of colors that can drive photosynthesis.


reaction center chlorophyll in the photosystem II.


reaction center cholophyll in the photosystem I

reaction center

the location of the first light driven chemical reaction of photosynthesis.

primary electron acceptor

specialized molecule that shares a reaction center with the chlorophyll a molecule in the light reaction. traps high energy electron before it can return to ground state in the chlorophyll.


iron containing protein in the photosystem I. passes the excited electron to NADP reductase to reduce NADP+

nadp+ reductase

enzyme in photosystem I that reduces nadp+ to form NADPH.


A small protein that shuttles electrons from photosystem II to photosystem I during photosynthesis.

cyctochrome complex

allows H+ to be pass through . passes the excited electron to the lastocyanin.


small protein that shuttles electrons from the primary e- acceptor to the cytochrome in photosystem II.


process by which a Hydrogen pump pumps protons into the thylakoid membrane. H+ passively flows thorugh the ATP synthase which leads to the creation of ATP


five carbon sugar in the calvin cycle. has a carbon molecule attached to it by rubisco


the most abundant protein in the chloroplasts in on eart. attaches a carbon to rubp to form a six carbon intermediate that splits in half to form two molecules of 3 phosphoglycerate.

1,3 bisphosphoglycerate

molecule formed as a result of an additional phosphate group from atp in the reducion phase of the calvin cycle.


sugar formed when nadph reduces 1,3-bisphosphoglyceride y adding electrons


how many cycles of the calvin cycle does it take in order to generate one whole glucose molecule


very inefficient process that occurs in c3 plants. occurs when oxygen instead of co2 is consumed by rubisco which fomrs a two carbon compound. leads to no atp. decreases photosynthetic output by sighoning organic material from the calvin cycle.

c3 plants

plants where the initial fixation of carbon occurs via rubisco.

c4 plants

plants that preface the calvin cycle with an alternate mode of carbon fixation that forms a four carbon compound as its first product. ex: sugarcane, corn, and members of the grass family

bundle sheath cells

cells in the leaf of c4 plants that ae arranged into tightly packed sheaths around the veins of the leaf. site of calvin cycle. receive co2 from mesophyll cells.

pep carboxylase

enzyme that adds co2 to pep. has a high affinity for co2 thus is more efficient at carbon fixation than rubisco.

mesophyll cell

loosely arranged cells in c4 plants that fix carbon to pep in order to release co2 to the bundle sheath cells through plasmodesmata.

CAM plants

succulent plants that open their stomata tduring the night and cloise them during the day to help plants in arid environments conserve water. take up co2 and incorporate it into a vareity of organic acids which can be released during the day to make sugar.

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