AP Bio Chapter 10 Photosynthesis
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Autotrophs
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organisms that use energy from sunlight or from chemical bonds in inorganic substances to make organic compounds
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Heterotrophs
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consumers, they rely on other organisms for their energy and food supply
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chlorophyll
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green pigment in plants that absorbs light energy used to carry out photosynthesis
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mesophyll
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specialized ground tissue that makes up the bulk of most leaves; performs most of a plant's photosynthesis
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stomata
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the small openings on the undersides of most leaves through which oxygen and carbon dioxide can move
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stroma
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The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.
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thylakoid
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A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy.
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thylakoid space
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region where hydrogen ions accumulate when water is split
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grana
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A stacked portion of the thylakoid membrane in the chloroplast. Grana function in the light reactions of photosynthesis
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6CO2+12H2O+light>C6H12O6+6O2+6H2O
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equation for photosynthesis
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C.B. Van Niel
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proposed that O2 is from H2O rather than CO2. Got 18O isotope with Atomic Weight of 18, labeled and watered plants. Measured atmospheric products.
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light reactions
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The steps in photosynthesis that occur on the thylakoid membranes of the chloroplast and that convert solar energy to the chemical energy of ATP and NADPH, evolving oxygen in the process.
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calvin cycle
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reactions of photosynthesis in which energy from ATP and NADPH is used to build high-energy compounds such as sugars
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photophosphorylation
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The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis.
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carbon fixation
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The incorporation of carbon from carbon dioxide into an organic compound by an autotrophic organism.
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photoautotroph
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organism that uses energy from sunlight to convert carbon dioxide and water to carbon compounds
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electromagnetic spectrum
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All of the frequencies or wavelengths of electromagnetic radiation
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visible light
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380-750 nm wavelength
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spectrophotometer
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An instrument that measures the proportions of light of different wavelengths absorbed and transmitted by a pigment solution.
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absorption spectrum
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the spectrum of electromagnetic radiation that has passed through a medium that absorbed radiation of certain wavelengths
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chlorophyll a
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absorbs best in the red and violet-blue wavelengths and least in the green.
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action spectrum
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the efficiency with which electromagnetic radiation produces a photochemical reaction plotted as a function of the wavelength of the radiation
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Thomas Engelmann
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scientist who took spirogyra (an algae) and reflected white light through a prism to see under which color bacteria grew most
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accessory pigments
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Pigment that absorbs light at different wavelengths and then pass energy onto chlorophyll
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chlorophyll b
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A type of yellow-green accessory photosynthetic pigment that transfers energy to chlorophyll a.
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cartenoids
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accessory pigments; absorb additional light that chlorophyll is unable to absorb; responsible for colors of the nonphotosynthetic parts of a plant (petals); ex: yellow, orange, brown; temp drops
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photoprotection
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Compound that absorb and dissipate excessive light energy that would otherwise damage chlorophyll or interact with oxygen, forming reactive oxidative molecules that are dangerous to the cell.
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fluorescence
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light emitted during absorption of radiation of some other (invisible) wavelength
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photosystems
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proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters
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light-harvesting complex
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A complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) that captures light energy and transfers it to reaction-center pigments in a photosystem.
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reaction center
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a group of electron transfer proteins that receive energy from light-absorbing pigments and convert it to chemical energy by redox reactions.
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primary electron acceptor
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in chloroplasts, an acceptor of electrons lost from chlorophyll a; found in the thylakoid membrane
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Photosystem I
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One of two light-harvesting units of a chloroplast's thylakoid membrane; it uses the P700 reaction-center chlorophyll.
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Photosystem II
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One of two light-harvesting units of a chloroplast's thylakoid membrane; it uses the P680 reaction-center chlorophyll.
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noncyclic electron flow
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A route of electron flow during the light reactions of photosynthesis that involves both photosystems and produces ATP, NADPH, and oxygen. The net electron flow is from water to NADP+.
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cyclic electron flow
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A route of electron flow during the light reactions of photosynthesis that involves only photosystem I and that produces ATP but not NADPH or oxygen.
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cyclic photophosphorylation
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The synthesis of ATP during photosynthesis, coupled to the cyclic passage of electrons to and from P700, the specialized form of chlorophyll a which is involved in photosystem I, using a series of carrier molecules.
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glyceraldehyde-3-phosphate
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A three-carbon carbohydrate that is the direct product of the Calvin cycle; it is also an intermediate in glycolysis.
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carbon fixation
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The incorporation of carbon from carbon dioxide into an organic compound by an autotrophic organism.
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reduction
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each 3-phosphoglycerate receives another phosphate group from ATP to form 1,3 bisphosphoglycerate. electrons from NADPH reduce each 1,2bisphosphoglycerate to G3P
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regeneration
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5 G3Ps remain in the cycle to regenerate 3 RuBP. the carbon skeletons are rearranged by he last steps of the calvin cycle.
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C3 Plants
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A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.
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photorespiration
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A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide.
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C4 plants
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A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into four-carbon compounds, the end product of which supplies CO2 for the Calvin cycle.
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Bundle-sheath cells
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A type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf.
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mesophyll cells
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A loosely arranged photosynthetic cell located between the bundle sheath and the leaf surface.
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PEP carboxylase
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adds CO2 to phoshoenolpyruvate (PEP) to form oxaloacetate. Has a very high affinity for CO2 and can fix CO2 eddiciently when rubisco cannot (arid conditions etc)
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CAM Plants
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Crassulacen acid metabolism. This plant stores carbon dioxide at night, and releases it during the day increasing the efficiency of photosynthesis.
