Ch. 4 - Photosynthesis Flashcards
Overall reaction:
6CO2 + 6H2O -> ____ + ____
____
C6H12O6
6O2
Noncyclic Photophosphorylation (ADP + Pi + light -> ____): light-dependent reaction.
ATP
Noncyclic Photophosphorylation
- Photosystem II: electrons trapped by P680 in PSII are ____ by light.
energized
Noncyclic Photophosphorylation
- ____: two excited e- passed to primary e- acceptor; primary because it is the first in chain of acceptor.
primary e- acceptor
Noncyclic Photophosphorylation
- E- transport chain: consists of a ____ which contains proteins like ____ and cofactor
Fe2+; analogous to ____
plastoquinone complex (PSII)
cytochrome
oxidative phosphorylation
Noncyclic Photophosphorylation
- Phosphorylation: 2e- move down ETC => ____ (energy used to phosphorylate about ____).
lose energy
1.5 ATP
Noncyclic Photophosphorylation
- Photosystem I: ETC terminates with PSI (P700); they are again ____ by sunlight and passed on to
another primary e- acceptor. From this point forward it can go to cyclic or noncyclic path.»_space;»If noncyclic…
energized
Noncyclic Photophosphorylation
- NADPH: 2e- then pass down a short ETC (with proteins like ____) to combine NADP+ + H+
+ 2e- => ____ (coenzyme) (only in noncyclic?).
ferrodoxin
NADPH
Noncyclic Photophosphorylation
- Splitting of Water (____): the loss of 2e- from PSII (initially) is replaced when H2O splits into ____, ____, and
____.(H+ goes for ____ formation and 1⁄2 O2 that contributes to release as ____). This occurs at PSII.
photolysis 2e- 2H+ 1/2O2 NADPH oxygen gas
Noncyclic Photophosphorylation
REACTION:
H2O + ADP + Pi + NADP+ + light => ____ + ____ + ____ + ____
ATP
NADPH
O2
H+
Note on photosystems: few hundred in each thylakoid, have a rxn center containing chlorophyll a surrounded by ____ that funnel energy to it.
antenna pigments
B. Cyclic Photophosphorylation: this replenishes ____ when Calvin cycle consumes it
- When excited 2e- from PSI join with protein carriers in the ____ electron transport chain and generate ____ as they pass through; these 2e- are recycled into PSI and can take either cyclic or noncyclic path.
ATP
first
1 ATP
C. Calvin Cycle: fixes CO2, repeat ____, uses 6CO2 to produce ____ (glucose). C3 photosynthesis (____)
6 times
glucose C6H12O6
dark reaction
Calvin Cycle
- Carboxylation: 6CO2 + 6RuBP => 12PGA, ____ (most common protein in the world, aka ____)
catalyzes this reaction. (so named because PGA is 3C).
Rubisco
RuBP carboxylase
Calvin Cycle
- Reduction: 12ATP + 12NADPH converts ____ => ____ or 12PGAL; energy is incorporated; by-products (NADP+
and ADP) go back into ____
12PGA
12G3P
noncyclic photophosphorylation
Calvin Cycle
- Regeneration: 6ATP convert ____ => ____ (allows cycle to repeat).
10G3P
6RuBp
Calvin Cycle
- Carbohydrate synthesis: 2 remaining ____ are used to build glucose.
____ + 18ATP + 12NADPH + H+ => 18ADP + 18Pi + 12NADP+ + ____
G3P
6CO2
1 glucose (2G3P)
Calvin Cycle
- This is the “dark reaction”, but it cannot occur w/out light because it is dependent on the ____
produced from the light rxn (____ and ____)
high energy molecules
ATP
NADPH
Calvin Cycle
Note: Bootcamp says that the energy used to drive the light-independent rxns comes from ____. ____ is what drives photosynthesis! And the energy in glucose traces back to ____ that gets stored in the form of glucose ____! Remember, plants do have mitochondria that make ATP, BUT: the ATP from photosynthesis comes from the ____ (not mitochondria) and is used to drive photosynthesis further (Calvin cycle). Photosynthesis primarily makes glucose for the plant’s own ____ to use as energy! Still need mitochondria for plant tissues but they don’t make the ATP for ____, and photosynthesis ATP isn’t used for general cell fxn!
light (photons) light energy light chemical bonds chloroplast mitochondria photosynthesis
D. Chloroplast: ____ and ____ reactions occur. (____ like mito + nucleus)
light-dependent
light-independent
double membrane
D. Chloroplast
- ____: plasma membrane (phospholipid bilayer)
- ____
- ____: also phospholipid bilayer.
- Stroma: fluid material that fills area inside inner membrane; ____ here (fixing ____ => ____)
outer membrane intermembrane space inner membrane calvin cycle CO2 G3P
D. Chloroplast
- Thylakoids: suspended within ____ (stacks); individual membrane layers are ____; entire stack is ____ membrane of thylakoids contain (PSI + PSII), cytochromes, and other e- carriers. Also phospholipid bilayer.
- Thylakoid lumen: interior of the thylakoid; ____ accumulates here.
stroma
thylakoids
granum
H+
D. Chloroplast
Note: Gradient uses ATP synthase to move the accumulated H+ from ____ to ____; H+ move from in to out to generate ATP via synthase……….
whereas in ox-phos we build up H+ ____ and then shuttle it back in to mitochondria to generate ATP via synthase
thylakoid membrane
stroma
outside
D. Chloroplast
Locations:
noncyclic photophos takes place in ____.
Cyclic phos takes place on ____ (pieces connecting the ____).
Photolysis takes place inside the ____ (passes e- to the membrane for noncyclic photophos).
thylakoid membranes
stroma lamellae
thylakoids
thylakoid lumen
D. Chloroplast
Calvin Cycle takes place in the ____.
Chemiosmosis takes place across the
____.
All of these take place ____ the chloroplast! Remember that is the ____, not the outer/inner chloroplast membranes, that absorb light!
stroma
thylakoid membrane
inside
thylakoid membrane
E. Chemiosmosis in Chloroplasts: uses ____ gradient to generate ATP.
H+
E. Chemiosmosis in Chloroplasts
- H+ ions accumulate inside ____: H+ are released into ____ when ____ is split by PSII. H+ is also carried into lumen from stroma by ____ between PSII and PSI.
thylakoid
lumen
H2O
cytochrome
E. Chemiosmosis in Chloroplasts
- A pH and electrical gradient is created: about ____.
pH 5
E. Chemiosmosis in Chloroplasts
- ATP synthase generates ATP: phosphorylate ADP + Pi => ATP. (____ is required for 1ATP).
3H+
E. Chemiosmosis in Chloroplasts
- Calvin cycle produces ____ using NADPH & CO2 & ATP: at the end of e- transport chain following PSI, 2e- produces
____.
2 G3P
NADPH
F. Photorespiration: fixation of ____ by ____ (can also fix ____) => produces no ATP or sugar.
Rubisco is not ____ because it will fix both ____ and ____ at the same time if both are present. Probably arose because early earth atmosphere didn’t have much ____ so it didn’t matter.
____ breakdown the products of this process (w/ Rubisco).
oxygen
rubisco
CO2
efficient
CO2
O2
O2
peroxisomes
G. C4 Photosynthesis: evolved from ____, when CO2 enters leaf; absorbed by ____ (then moved to ____);
instead of being fixed by rubisco into PGA, CO2 combines with ____ to form ____ by ____ (in mesophyll)
C3
mesophyll cells
bundle sheath
PEP
OAA
PEP carboxylase
G. C4 Photosynthesis
- OAA has 4C => C4 photosynthesis.
- OAA => ____ and then transported through ____ into ____
- Malate => pyruvate + CO2. (CO2 can be used into Calvin cycle) (Pyruvate moved back to ____ then => PEP)
malate
plasmodesmata
bundle sheath cell
mesophyll
G. C4 Photosynthesis
- Overall purpose is to ____ to ____ (structure = Kranz anatomy, process = Hatch- Slack pathway (little O2 presence reduces competition while rubisco is fixing).
Minimize ____ and ____ loss from stomata (leaf pores); found in ____ climates (faster fixation speed and more efficient).
Requires one additional ____ (which becomes AMP). C3 typically occurs in ____, but in C4 it occurs in ____. Corn, sugarcane
mesophyll
bundle sheath cell
photorespiration
H2O
hot, dry
ATP
mesophyll
bundle sheath cells
H. CAM Photosynthesis:
- Another add-on to C3, ____; almost identical to C4.
crassulacean acid metabolism
H. CAM Photosynthesis
- PEP carboxylase fixes CO2 + PEP to OAA; OAA => ____.
- MA is shuttled into ____ of cell.
malic acid
vacuole
H. CAM Photosynthesis
- At night, stomata are ____ (opposite of normal), PEP carboxylase is ____, malic acid ____ in vacuole.
- During day, stomata are ____. Malic acid is ____ of vacuole and converted back to OAA (require ____), releasing ____
(moved onto ____ with rubisco) and PEP.
open
active
accumulates
closed out 1 ATP CO2 calvin cycle
H. CAM Photosynthesis
- Overall advantages are can proceed during day while stomata are closed (reduce ____). Cacti, crassulacea plants,
H2O loss
- As leaves age, chlorophyll ____ to extract valuable components like ____, carotenoids are ____.
breaks down
Mg2+
visible
- Splitting of H2O provides 2e- for noncyclic photophosphorylation; incorporated into ____ and ____.
NADPH
Calvin cycle
- Calvin cycle is light-independent, but it requires ____ and ____ produced from light-dependent rxn.
ATP
NADPH (produced from LIGHT)
____ (chlorophyll b, carotenoids, phycobilins [red algae pigment], xanthophylls) capture wavelegnths that ____ does not, passes energy to chlorophyll a where ____ occurs.
Chlorophyll a has ____ (alternating double and single bonds, double bonds critical for light rxns) complexed w/ ____ inside.
antenna proteins
chlorophyll a
direct light rxn
porphyrin ring
Mg atom
