1.
3-PGA: 3-phosphoglycerate; 2 3-C molecules from RuBP catalyzed breakdown by rubisco
2.
antenna pigments: chlorophyll b & carenoids; capture wavelengths other than those of chlorophyll a in photosystem & pass energy via photons
3.
C-3 plants: Most plants; first step produces 3-PGA. NOT very effecient b/c rubisco binds w/ O2 as well as CO2. if O2, photorespiration => peroxisomes break down producs.
4.
C-4 plants: hot, dry environments. Different Kranz anatomy/pathway. Minimizes water loss & maximizes sugar production. Mesophyll, Hatch-Slack pathway: CO2 + 3C PEP =PEP carboxylase=> oxaloacetate => malic acid (malate). Bundle-sheath cell: malate => CO2 => Calvin Cycle.
5.
Calvin cycle: dark rxns, cyclical process that produces the sugar PGAL. CO2 fixed/incorporated into PGAL. Carbon fixation. Reduction rxn b/c C gains H. CO2 + RuBP =rubisco=> 3-PGA. Depends on PRODUCTS of light rxns, ATP & NADPH. Occurs ONLY in light, in ALL plants.
6.
CAM plants: all mesophyll cells; crassulacean acid metabolism; dry conditions; opposite of normal. NIGHT: stomata OPEN, store CO2 in organic compounds (malate). DAY: stomata CLOSED, light rxns supply energy for Calvin cycle & CO2 is released from organic acids
7.
carbon fixation: a reduction reaction since carbon gains hydrogen, the incorporation of CO2 into PGAL
8.
cartenoids: are yellow, orange, red; absorb blue, green, violet
9.
chemiosmosis (photosynthesis): process by which ATP is formed during light rxns; protons released by photolysis of H2O pumped by thylakoid membrane; stroma => thylakoid space. ATP formed as H+ diffuse down back into the stroma thru ATP synthase. This ATP powers the Calvin cycle.
10.
chlorophyll a: directly involved in light rxns; large molecule w/ a head called the porphyrin ring w/ a magnesium atom @ the center; long hydrocarbon tail <= double bonds are source of e- for ETC
11.
chloroplast (grana, thylakoid, stroma): grana => thylakoids => thylakoid membrane: where light rxns occur. Stroma: where dark rxns occur. Surrounded by double membrane.
12.
chrlorophyll: is green; absorbs red, blue, violet
13.
cyclic photophosphorylation: sole purpose: produce ATP. NO NADPH is produced, NO oxygen is released (No H2O used). Occurs because Calvin cycle consumes enormous amounts of ATP compared to NADPH, so occurs when cell is low-ATP. travel from the P680 ETC (not P680 itself) to P700, to primary e- acceptor, and back to cytochrome complex (where ATP is synthesized). - review diagram p.138
14.
electron transport chain (photosynthesis): NONCYCLIC: e- pass via plastoquinone (PQ), 2 cytochromes, other proteins => P700. Exergonic => provides energy for production of ATP by chemiosmosis, like in respiration. Diagram p.137
15.
Hatch-Slack pathway: the alternate biochemical pathway in C-4 plants (mesophyll cels) to remove CO2 from the air space near the stomata. Creates a steep CO2 gradient between the air and mesophyll => can get lots of CO2, minimizes time stomata open
16.
Kranz anatomy: structure of C-4 leaves that differs from C-3 leaves. C-4: CO2 sequestered deep in bundle-sheath cells. C-3: all photosynthetic cells have direct access to CO2.
17.
light dependent reactions: light reactions; use light energy directly to produce ATP
18.
light independent reactions: dark reactions; Calvin cycle; produces sugar; uses ATP of light rxn. ALSO occurs ONLY when light is present
19.
malic acid: aka malate; produced from oxaloacetate in C-4 plants and in CAM plants directly from CO2
20.
NADP/NADPH: electron carrier of photosynthesis; is REDUCED (NADP+ => NADPH) when it picks up 2 protons released by water in photolysis. Carries H+ to Calvin cycle.
21.
noncyclic photophosphorylation: electrons enter two ETCs and ATP AND NADPH are formed. light => P680, oxygen released => ATP produced => P700 => NADPH produced (carries H+ to the Calvin cycle) Diagram p.136
22.
PEP: phosphoenolpyruvate; the 3-C carbon molecule that CO2 combines with to form oxaloacetate in C-4 plants.
23.
PEP carboxylase: C-4 plants; enzyme catalyzes CO2 + 3C PEP =PEP carboxylase=> oxaloacetate
24.
peroxisomes: break down the products of photorespiration
25.
PGAL (G3P): phosphoglyceraldehyde; 3-C sugar produced from the Calvin cycle
26.
photolysis: step 2 in NONCYCLIC photophosphorylation ONLY; after electrons are absorbed by the primary electons, water is split to replace e- lost from P680. splits water => 2 e- (replacing), 2 H+ (combine w/ NADP+ and 2e- later), and one oxygen (O2 => gas released as byproduct)
27.
photophosphorylation: ATP synthesis powered by light (via e- down an ETC and an ATP synthase)
28.
photorespiration: when rubisco binds to O2 in C-3 plants; diverts the process of photosynthesis in 2 ways: 1) Unlike normal respiration, no ATP produced. 2) Unlike normal photosynthesis, no sugar formed. Instead peroxisomes breakdown products. Vestige from ancient low-O2 atmosphere.
29.
photosynthesis (PS): the process by which light energy is converted to chemical bond energy and carbon is fixed into organic compounds
30.
photosynthesis equation: 6CO2 + 12H20 =light=> C6H12O6 + 6H2O + 6 O2
31.
photosynthetic pigment: absorb light energy; use it to provide energy for PS. two major groups: chlorophylls and cartenoids
32.
photosystem: light-harvesting complex in thylakoid membrane; few hundred photosystems/thylakoid. Each consists of a reaction center. PSI & PSII
33.
phycobilins: red algae; absorb blue, green
34.
primary electron acceptor: present in the photosystems (I and II), captures the electrons that are energized when light energy is absorbed by chlorophyll a
35.
PS I: the second photosystem; absorbs light best @ P700; NONCYCLIC: energized in same way (by light), but e- replaced by e- coming from the ETC from P680, instaed of water. ends with production of NADPH, not ATP. CYCLIC: recycles the same e- in a loop to produce ATP ONLY!! e- go back to cytochrome instead of to NADPH.
36.
PS II: the first photosystem; absorbs light best @ P680; electrons from double bonds of chlorophyll a become energized & move to higher energy level, captured by primary electron acceptor. NONCYCLIC ONLY!!
37.
reaction center: part of the photosystem that contains chlorophyll a and a region w/ several hundred antenna pigment molecules that funnel energy to chlorophyll a
38.
rubisco: ribulose biphosphate carboxylase; enzyme that catalyzes the reaction of RuBP (6C) => 1 3-PGA
39.
RuBP: ribulose biphosphate; combines with 3CO2 to form a 6-C molecule, unstable, immediately breaks down into 3-PGA catalyzed by rubisco
40.
xanthophyll: cartenoid with a slight chemical variation
