CH 10 Flashcards
Chloroplasts
-organelles in plants and other photosynthetic organisms
Photosynthesis
-the process that converts solar energy into chemical energy within chloroplasts
Autotrophs
-“self-feeders”
-sustain themselves without eating anything derived from other organisms
-produce biosphere
Heterotrophs
-obtain organic materials from other organisms
-consumers of the biosphere
Mesophyll
-interior tissue of the leaf
-where chloroplasts are found
Stomata
-microscopic pores where CO2 enters and O2 exits
stroma
-a dense fluid surrounded by two mwmbranes
Thylakoids
-connected sacs in the chloroplast that compose a third membrane system
-maybe stacked in columns called grana
Chlorophyll
-the pigment that gives leaves their green color
-resides in thylakoid membranes
Light reactions
-photo part of photosynthesis
inputs and outputs of light reactions
-inputs–light, H2O
-outputs–O2
How are the light reactions and chemiosmosis related?
-they both are used to produce ATP
Photophosphorylation
-generates ATP from ADP
Carbon fixation
-initial incorporation of carbon into organic compounds
Wavelength
-the distance between crests of electromagnetic waves
-determines the type of electromagnetic energy
Electromagnetic spectrum
-the entire range of electromagnetic energy, or radiation
Visible light
-consists of wavelengths (380 nm to 750nm) that produce colors we can see
Photons
-discrete particles
Spectrophotometer
-measures a pigment’s ability to absorb various wavelengths
Absorption spectrum
-a graph plotting a pigments light absorption versus wavelength
Chlorophyll a
-key light-capturing pigment
Chlorophyll b
-accessory pigment
Action spectrum
-profiles the relative effectiveness of different wavelengths of radiation in driving a process
Carotenoids
-accessory pigments
-broaden the spectrum of colors that drive photosynthesis
Photosystem
-consists of a reaction-center complex surrounded by light-harvesting complexes
Reaction-center complex
-an association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor
Light-harvesting complex
-consists of pigment molecules bound to proteins
Primary electron acceptor
-accepts excited electrons and is reduced as a result
-in the reaction center
Photosystem II (PS II)
-reaction-center chlorophyll a of PS II is called P680
-best at absorbing a wavelength of 680 nm
-functions first
Photosystem I (PS I)
-reaction-center chlorophyll a of PS I is called P700
-best at absorbing a wavelength of 700 nm
Linear electron flow
-primary pathway, involves both photosystems and produces ATP and NADPH using light energy
Cyclic electron flow
-electrons cycle back from Fd to the PS I reaction center via a plastocyanin molecule (Pc)
-uses only photosystem I and produces ATP, but not NADPH
-no O2 released
Calvin cycle
-synthesis part of photosynthesis
-regenerates its starting material after molecules enter and leave the cycle
-is anabolic
what are the Calvin cycle inputs and outputs
-inputs– 3 CO2
-outputs–G3P
three phases of the Calvin cycle
-Carbon fixation
-reduction
-Regeneration of the CO2 acceptor (RuBP)
what is regenerated to keep the Calvin cycle going?
-RuBP (Ribulose biphosphate)
G3P (glyceraldehyde 3-phosphate)
-three-carbon sugar
Carbon fixation
-initial incorporation of carbon into organic compounds
-catalyzed by rubisco
Rubisco
-RuBP carboxylase-oxygenase
reduction
-the gain of electrons by a molecule
regeneration of the CO2 acceptor (RuBP)
-Rubisco converts carbon dioxide into sugars that help plants grow and function
Photorespiration
-rubisco adds O2 instead of CO2 in the Calvin cycle, producing a two-carbon compound
C3 plants
-first organic product of carbon fixation is a three-carbon compound (3-phosphoglycerate)
C4 plants
-preface the Calvin cycle with an alternative mode of carbon fixation that forms a four-carbon compound
-minimize the cost of photorespiration by incorporating CO2 into four-carbon compounds
Bundle-sheath cells
-arranged in tightly packed sheaths around the veins of the leaf
PEP carboxylase
- an enzyme present in only mesophyll cells
Crassulacean acid metabolism (CAM)
-mode of carbon fixation
-adaptation that allows it to photosynthesize during the day and exchange gasses at night
CAM plants
-plants that photosynthesize during the day and exchange gasses at night
