5 Flashcards
- Equation that summarizes PHOTOSYNTHESIS – The reactants, products and the number of molecules (Balance the equation)
6 H2O + 6 CO2 —–> 6 O2 + C6-H12-O6
- State where chlorophyll is located in a chloroplast and the function of chlorophyll in photosynthesis.
Found in the photosystems which are anchored in thylakoid membranes. A few hundred chlorophyll a (in antennae pigments) surround a reaction center which has a pair of special/modified chlorophyll a. The antennae pigment chlorophyll absorb light energy and pass it to the reaction center chlorophyll. Electrons are energized in the reaction center before being ejected to the ETC.
What is Photosynthesis?
A metabolic process where organisms (plants, algae and some microorganisms) harness the energy of light to build organic molecules from inorganic raw materials.
What wavelength of light drives photosynthesis?
380-750nm
What is a pigment?
An organic molecule that selectively absorbs light of specific wavelengths.
Main points - light-dependent reactions.
Light energy (required) is transferred to ATP and NADPH (produced). Water molecules (required) are split releasing o2 (byproduct).
Main points - light independent reactions.
Energy in ATP and NADPH drives synthesis of glucose and other carbohydrates from CO2.
Electron transfer chain
Organized arrays of enzymes, coenzymes, and other proteins that accept and donate electrons in a series of redox reactions.
Describe C4 plant
Light reactions occur in mesophyll cells as does a carbon-fixation pathway called the C4 pathway. CO2 combines with 3C molecule to form 4C oxaloacetate which is usually reduced to a malate. Malate moves into adjacent bundle sheath cells where the CB cycle fixes carbon a second time. Arrangement increases efficiency, bs cells are isolated from O2 rich air.
Describe CAM plant
Crassulacean acid metabolism plants use temporal separation to increase efficiency. Stomata open at night, mesophyll cells incorporate CO2 into malate and store it in vacuoles. During the day, stored malate is moved into chloroplasts, release CO2, CO2 is fixed in cb cycle.
Calvin Benson cycle (carbon reactions)
CB cycle is a series of reactions that result in the conversion of CO2 into organic molecules. 1st reaction is carbon fixation. Catalyzed by rubisco, CO2 is added to ribulose biphosphate carboxylase/oxygenase (RuBP) forming an unstable intermediate. This intermediate splits into phosphoglycerate (PGA) in the 2ndstep,PGALsynthesis. Using electrons and hydrogen of NADPH and the energy (phosphate group) of ATP (both supplied from light reactions), the PGA is converted into phosphoglyceraldehyde (PGAL). Some of the PGAL is used to form glucose (2 PGAL per glucose). The other PGAL is used in regeneration, the last step. Powered by ATP, the PGAL is rearranged into RuBP and the cycle can continue.
LDR - 1 (photosystem II)
Chlorophyll transfers light energy to electrons. Pigment molecules absorb light and transfer the energy to the reaction center where it boosts 2 electrons to an orbital with higher energy. The 2 electrons are ejected from the reaction center and grabbed
LDR - 2 (electron repacement)
These 2 electrons are replaced in photosystem II by hydrolysis. A molecule of water is split into 1/2 O2, 2H+ and 2 electrons. The 1/2 O2 is doubled and either released to the environment or used in respiration. The H+ remains in the thylakoid space.
LDR - 3 (e.t.c. I)
As electrons pass along ETC I, the energy they lose is used to pump H+ into the thylakoid space from the stroma creating a gradient across the thylakoid membrane.
LDR - 4 (ATP synthase)
ATP sythase (enzyme complex) transforms the potential energy from the gradient to ATP. Energy is released as the gradient dissipates from H+ moving thru ATP synthase. This energy is used to add a phosphate to ADP creating ATP.
