79 Key Terms
- absorption spectrum
- range of wavelengths of electromagnetic radiation absorbed by a given substance
- antenna protein
- pigment molecule that directly absorbs light and transfers the energy absorbed to other pigment molecules
- Calvin cycle
- light-independent reactions of photosynthesis that convert carbon dioxide from the atmosphere into carbohydrates using the energy and reducing power of ATP and NADPH
- carbon fixation
- process of converting inorganic CO2 gas into organic compounds
- carotenoid
- photosynthetic pigment (yellow-orange-red) that functions to dispose of excess energy
- chemoautotroph
- organism that can build organic molecules using energy derived from inorganic chemicals instead of sunlight
- chlorophyll a
- form of chlorophyll that absorbs violet-blue and red light and consequently has a bluish-green color; the only pigment molecule that performs the photochemistry by getting excited and losing an electron to the electron transport chain
- chlorophyll b
- accessory pigment that absorbs blue and red-orange light and consequently has a yellowish-green tint
- chloroplast
- organelle in which photosynthesis takes place
- cytochrome complex
- group of reversibly oxidizable and reducible proteins that forms part of the electron transport chain between photosystem II and photosystem I
- electromagnetic spectrum
- range of all possible frequencies of radiation
- electron transport chain
- group of proteins between PSII and PSI that pass energized electrons and use the energy released by the electrons to move hydrogen ions against their concentration gradient into the thylakoid lumen
- granum
- stack of thylakoids located inside a chloroplast
- heterotroph
- organism that consumes organic substances or other organisms for food
- light harvesting complex
- complex that passes energy from sunlight to the reaction center in each photosystem; it consists of multiple antenna proteins that contain a mixture of 300 to 400 chlorophyll a and b molecules as well as other pigments like carotenoids
- light-dependent reaction
- first stage of photosynthesis where certain wavelengths of the visible light are absorbed to form two energy-carrying molecules (ATP and NADPH)
- light-independent reaction
- second stage of photosynthesis, through which carbon dioxide is used to build carbohydrate molecules using energy from ATP and NADPH
- mesophyll
- middle layer of chlorophyll-rich cells in a leaf
- P680
- reaction center of photosystem II
- P700
- reaction center of photosystem I
- photoact
- ejection of an electron from a reaction center using the energy of an absorbed photon
- photoautotroph
- organism capable of producing its own organic compounds from sunlight
- photon
- distinct quantity or “packet” of light energy
- photosystem
- group of proteins, chlorophyll, and other pigments that are used in the light-dependent reactions of photosynthesis to absorb light energy and convert it into chemical energy
- photosystem I
- integral p