LESSON 3c: Photosynthesis Flashcards
-get their energy from “eating others”
-make energy through respiration
Heterotrophs (Animals)
- produce their own energy (from “self”)
- convert energy of sunlight
- build organic molecules (CHO) from CO2
- make energy & synthesize sugars through
photosynthesis
Autotrophs (Plants)
making energy & organic molecules from ingesting organic molecules
Heterotrophs
(Give the formula) glucose + oxygen —> carbon dioxide + water + energy
C6H12O6 + 6O2 —> 6CO2 + 6H2O + ATP
making energy & organic molecules from light energy
Autotrophs
(Give the formula) carbon + water + energy – >glucose + oxygen
6CO2 + 6H2O + Light Energy —> C6H12O6 + 6O2
-collect light energy
-transform it into chemical energy
-store light energy
-need to get building block atoms
from the environment
- produce all organic molecules
needed for growth
Plants
Obtain Sunlight
Leaves
Leaves
Solar Collectors
Obtain CO2
Stomates
Stomates for _________
Gas Exchange
Obtain water
roots
Nutrients that is obtained by roots
-Nitrogen
-Phosphorus
-Potassium
-Sulfur
-Magnesium
-Iron
absorb light and CO2 and make energy & sugar
Chloroplasts
Chloroplast contains ___________
Chlorophyll
Parts of Chloroplasts
-Double membrane
-Stroma
-Thylakoid sacs
-Grana Stacks
fluid-filled interior
Stroma
Thylakoid membrane contains
-chlorophyll molecules
-electron transport chain
-ATP synthase
H+ gradient built up within
thylakoid sac
ATP synthase
Types of Light Reactions
-light-dependent reactions
-energy conversion reactions
-convert solar energy to chemical energy
-ATP & NADPH
energy conversion reactions
-uses chemical energy (ATP & NADPH) to reduce CO2 & synthesize C6H12O6
sugar building reactions
Calvin Cycle include _____________
-light-independent reactions
-sugar building reactions
Light Reactions like in cellular respiration
Electron Transport Chain
Light Reaction electron Acceptors
NADPH
Mitochondria transfer chemical energy from food molecules into ________________________
chemical energy of ATP
ETC of Respiration use electron Carrier ___________
NADH
Chloroplasts transform________ into chemical energy of ATP
light energy
ETC of photosynthesis used electron carrier _____
NADPH
The ATP that “jack” built Photosynthesis
Sunlight
To do photosynthesis/respiration, sunlight/breakdown of Glucose allows the ff.
§ moves the electrons
§ runs the pump
§ pumps the protons
§ builds the gradient
§ drives the flow of protons
through ATP synthase
§ bonds Pi to ADP
§ generates the ATP
The ATP that “jack” built respiration is
Breakdown of Glucose (C6H12O2)
- embedded in thylakoid membrane
- arranged in a “photosystem”
- structure-function relationship
Chlorophylls & other pigments
Chlorophylls & other pigments is arrange in a _________
Photosystem
Shorter wavelength–> longer wavelength]
and
Higher energy to lower energy
-Gamma Rays > X-ray > UV > Infrared > Microwaves > Radio waves
Photosynthesis gets energy by ___________
absorbing
wavelengths of light
absorbs best in red & blue wavelengths & least in green
chlorophyll a
accessory pigments with different structures absorb light of different wavelengths
-chlorophyll b,
-carotenoids,
-xanthophylls
- collections of chlorophyll molecules
-act as light-gathering molecules
2 photosystems in thylakoid membrane
-chlorophyll a
- P680 = absorbs 680nm
wavelength red light
Photosystem II
-chlorophyll b
-P700 = absorbs 700nm
wavelength red light
Photosystem I
ETC uses light energy to produce
ATP & NADPH
PS II absorbs light
- excited electron passes from chlorophyll to
“primary electron acceptor” - need to replace electron in chlorophyll
- enzyme extracts electrons from H2O & supplies them to chlorophyll
Where did the O2 come from?
radioactive tracer = O18
Proved O2 came from H2O not CO2 =________
plants split H2O
Light reactions elevate
electrons in 2 steps (PS II & PS I)
Noncyclic Phosphorylation
PS II generates
energy as________
ATP
PS I generates
reducing power as ________
NADPH
-If PS I can’t pass electron to
NADP…it cycles back to PS II &
makes more ATP, but no NADPH
-coordinates light reactions to
Calvin cycle
-Calvin cycle uses more ATP than
NADPH
Cyclic Phosphorylation
18 ATP + 12 NADPH —> _________
1 C6H12O6
Light reactions converts solar energy to ___________________
Chemical energy
____has very little chemical energy
CO2
__________ contains a lot of chemical energy
C6H12O6
-proceeds in many small
uphill steps
-each catalyzed by specific enzyme
-using energy stored in ATP & NADPH
Reduction of CO2 —-> C6H12O6
Calvin cycle in plants happens in ______
Chloroplast stroma
Calvin cycle need products of light reactions to drive synthesis reactions. What are the products?
-ATP
-NADPH
-end product of Calvin cycle
- energy rich 3 carbon sugar
-“C3 photosynthesis”
Glyceraldehyde-3-P (G-3-P)
G-3-P can be convert to ____________
-glucose–> carbohydrates
-Lipids
-Amino acids
-nucleic acids
-Enzyme which fixes carbon from air
-the most important enzyme in the world
-definitely the most abundant
RUBISCO
RUBISCO
ribulose bisphosphate carboxylase
3 turns of Calvin cycle (Plants) =_____
1 G3P
3 CO2 –> _______
1 G3P (3C)
6 turns of Calvin cycle =
1 C6H12O6 (6C)
6 CO2 –>_____
1 C6H12O6 (6C)
18 ATP + 12 NADPH –> ________
1 C6H12O6
any ATP left over from light reactions will be used __________ by the cell
elsewhere
-produced ATP
-produced NADPH
-consumed H2O
-produced O2 as byproduct
Light Reactions
- consumed CO2
- produced G3P (sugar)
- regenerated ADP
- regenerated NADP
Calvin Cycle
During Photosynthesis, light reactions need light from _________ and H2O from _________
-Sun
-ground
During Photosynthesis, calvin cycle needs CO2 from __________
Air
CO2 in
Calvin Cycle
O2 out
waste from Light reaction
H2O out
Light reactions
how plants control water loss from leaves?
-stomates close to conserve water
When guard cell gain H2O, stomates _____
open
when guard cells lose H2O, stomates _____
close
Closed stomates leads to?
-O2 builds up –> from light reactions
- CO2 is depleted –> in Calvin cycle (which cause problems)
Rubisco in Calvin Cycle
-carbon fixation enzyme (Photosynthesis)
-when O2 concentration is high (Photorespiration)
carbon fixation enzyme
-normally bonds C to RuBP
-reduction of RuBP
-building sugars
when O2 concentration is high
-Rubisco bonds O to RuBP
-O2 is alternative substrate
-oxidation of RuBP
-breakdown sugars
-short circuit of Calvin cycle
-loss of carbons to CO2
-reduces production of photosynthesis
-if photorespiration could be reduced, plant would become 50% more efficient
Oxidation of RuBP
-physically separate carbon fixation from actual Calvin cycle
- different enzyme to capture CO2
-PEP carboxylase stores carbon in 4C
compounds
-different leaf structure
C4 Plants
- separate carbon fixation from actual Calvin cycle by time of day
- fix carbon (capture CO2) during night
- store carbon in organic acids
- perform Calvin cycle during day
CAM Plants
C4 Plants: 1st step before Calvin cycle,
fix carbon with enzyme
______________
PEP carboxylase
PEP carboxylase is store as ______________
4C Compound
Example of C4 Plants
Sugar Cane, Corn and other grasses
-higher affinity for CO2 than O2 (better than Rubisco)
-fixes CO2 in 4C compounds
-regenerates CO2 in inner cells for Rubisco
PEP carboxylase enzyme
phosphoenolpyruvate (3C) + CO2–>____________
oxaloacetate (4C)
Separate reactions in different cells
-light reactions
-carbon fixation
-Calvin cycle
C4 Photosynthesis: -light reaction &
carbon fixation
-pumps CO2 to inner cells
-keeps O2 away from inner cells
Outer cells
C4 Photosynthesis: -Calvin cycle
-glucose to veins
Inner Cells
CAM Plants
Crassulacean Acid Metabolism
CAM Plants: Different adaptation to hot, dry climates
-separate carbon fixation from Calvin cycle by time
-at night, open stomates & fix
carbon in “storage” compounds
-in day, close stomates & release CO2 from
“storage” compounds to Calvin cycle
Organic Acids stored in stomates of CAM Plants as mentioned in the PPT
-Malic Acids
-Isocitric Acid
examples of CAM plants
-Succulent
-some cacti
-pineapple
C4 Plants VS. CAM Plants
-C4 plants
separate 2 steps of C fixation anatomically in 2 different cells
-CAM plants
separate 2 steps of C fixation temporally at 2 different times
-most plants
-fix carbon in Calvin cycle (Attach CO2 to RuBP)
-Enzyme: Rubisco
-Most Energy efficient method
-losses water through photorespiration
C3 Plants
-Tropical grasses (corn, sugar cane)
-Fix carbon in cytoplasm (attach CO2 to PEP
-Enzyme: PEP-ase
-1/2 way between C3 and CAM
-Losses less water
C4 Plants
-Succulents, pineapples, agave
-fix carbon at night only, fix it to organic molecules
-Enzyme: PEP-ase
-Best Water Conservation
-Loses least water
CAM Plants
Possibly evolutionary baggage
-Rubisco evolved in high CO2 atmosphere
(there wasn’t strong selection against active site of Rubisco accepting both CO2 & O2)