Lc 9. Alternative Energy and Alternative Carbon Sources Flashcards
What are chemoheterotrophs?
Organisms that use cellular respiration. The carbon source is organic (contains C and H, ex. glucose). The energy source is also organic (contains C and H, ex. glucose).
What are photoautotrophs?
Organisms that use photosynthesis. The carbon source is inorganic (CO2). The energy source is light.
What is photosynthesis as a redox process?
H2O is oxidized and CO2 is reduced. It is an endergonic process; the energy input is provided by light.
What are the two steps of photosynthesis?
Light-dependent reaction and Calvin Cycle (Light-independent) reactions.
What is light?
Electromagnetic energy – aka electromagnetic radiation, travels in waves, measured in wavelength.
What is the electromagnetic spectrum?
The entire range of electromagnetic energy or radiation.
What wavelength range drives photosynthesis?
Visible light (380 nm to 740 nm) drives photosynthesis and produces the colors seen by the human eye.
What are the major pigments in chloroplasts?
Chlorophyll a (key light-capturing pigment), Chlorophyll b (accessory pigment), and Carotenoids (accessory pigments that can be protective).
What happens when chlorophyll absorbs light?
An electron goes from a ground state (stable) to an excited state (unstable). In isolation, excited electrons fall back to the ground state, releasing excess energy as heat or light, an afterglow called fluorescence.
What do light-harvesting complexes do?
Pigments absorb photons and transfer energy.
What is the role of the reaction center in photosystems?
Chlorophyll a transfers electrons to the primary electron acceptor, which is then reduced.
What occurs in Photosystems I and II?
Photophosphorylation occurs in the thylakoid membrane.
What is the equation for the light-dependent reactions?
2H2O + 2NADP+ + 3ADP + 3Pi → O2 + 2NADPH + 3ATP.
What does the Calvin cycle do?
Uses the chemical energy of ATP and NADPH to reduce CO2 to sugar. It is anabolic; it builds sugar from smaller molecules.
What are the three phases of the Calvin cycle?
Carbon fixation, reduction, and regeneration of the CO2 acceptor.
What happens in Phase 1 of the Calvin cycle?
CO2 binds to ribulose bisphosphate (RuBP) catalyzed by rubisco, forming a six-carbon intermediate that splits into two molecules of 3-phosphoglycerate.
What happens in Phase 2 of the Calvin cycle?
Each 3-phosphoglycerate is phosphorylated by six ATP and reduced by six NADPH to produce 1 G3P sugar.
What happens in Phase 3 of the Calvin cycle?
The remaining five molecules of G3P are rearranged to yield three molecules of RuBP, using three additional ATP.
What are chemoautotrophs?
Organisms that use cellular respiration. The carbon source is inorganic (CO2) and the energy source is also inorganic (ex. H2S).
