Chapter 10 - Photosynthesis Flashcards
Define photosynthesis
Capturing energy stored in light and converting it into chemical energy in glucose
Auto troughs versus heterotrophs
Autotroph’s produce organic molecules from an organic raw materials and CO2, heterotrophs nutrition
Producers, consumers, and decomposers
What organisms are photoautotrophs
Plants, algae, non-algal unicellular eukaryotes, cyanobacteria prokaryotes, other prokaryotes
Endo symbiotic theory: how did chloroplasts evolve
The outer membrane of an organism were enfolded and eventually created independent organelles, bacteria
Parts of the plant: mesophyll stomata stroma thylakoid chlorophyl
- tissue in interior of leaf
- microscopic pores on leaf, carbon dioxide enters and oxygen exits
- dense fluid, cytoplasm of the chloroplast
- third membrane, socks, stacked in grannum occasionally
The product of oxygen in photosynthesis comes from which reactant? Which reactant is reduced and which is oxidized? Where does each element of the reactance go of the products?
Comes from splitting of water, carbon dioxide is reduced, water is oxidized
Carbon to glucose, oxygen of carbon dioxide to glucose and water, hydrogen to water and glucose, oxygen and water to oxygen waste.
Photosynthesis is separated into which two processes
Light reactions and Calvin cycle
Light reactions capture light energy, Calvin cycle synthesizes organic molecules
What is photophosphorylation
Chemiosmosis powered by light reactions of ADP to make ATP
What is carbon fixation
Incorporating carbon into organic compounds
What powers the energy needed in Calvin cycle
NADPH from the light reactions and ATP from light reactions
Where do light reactions occur? Where does the Calvin cycle occur? Where is NADPH and ATP released? Where is concentration of hydrogen and where is the ATP synthase?
I’ll Coit and buy liquid membrane, all rest stroma,
How does wavelength correlate with energy?
Smaller wavelength higher energy, Violet light almost 2 times more energy than red light
Electromagnetic spectrum: what’s the range of visible light, what are the wavelength measurements, where are the colour is situated?
380 nm 759 nm, purple is 380 red is 750
What’s a photon
Particle of light energy with specific wavelengths, particle and wave properties
What range on the electromagnetic spectrum does photosynthesis use? Explain the action spectrum for chloroplasts using the three pigments of chlorophyl a, chlorophyl B, and carotenoids.
Visible light
Chlorophyl a absorbs purple and orange light, chlorophyl be absorbs purple blue and orange red light, carotenoids absorb purple blue blueish green light. Green light is not absorbed and reflected so plants appear green.
Theodore W Engleman experiment of action spectrum for chloroplasts
Used aerobic bacteria growth on the filament of algae to determine oxygen output for determining amount of photosynthesis happening at specific wavelengths
What’s the difference between chlorophyl a and chlorophyl B
Chlorophyll eight is a blue green cloth B is olive green, chlorophyll a absorbs less than chlorophyll bees range. Chlorophyll eight is the key like caption pigment, chlorophyll B is an accessory pigment.
What role do carotenoids play in photoprotection
They absorb anticipate excessive light energy that would otherwise damage chlorophyl or form reactive oxidative molecules when interacting with oxygen, also protective role in human eye
What happens when chlorophyl absorbs light
One electron is elevated to an orbital with more potential energy, pigment is in excited state. Ground state is original electron location. Excited state is highly unstable, most electrons drop back down releasing energy as heat, photons given off creating florescence (red yellow glow)
Explain the structure of a photosystem
Reaction centre complex: special pair of chlorophyll a molecules, primary electron acceptor, chlorophyl boost electron to higher level
Harvesting complex: various pigment molecules bound to proteins (antenna), pigments transfer their energy to other pigments instead of boosting electron
How are deoxidized pair of chlorophyl molecules in the reaction centre complex a photosystem one replenished
By the splitting of water, it gets its electrons with hydrogen
What are the reaction centre chlorophyl is a photosystem one and photosystem two
Photosystem two is P6 80 photosystem one is P 700, those are the best wavelengths for absorption
Briefly summarize the steps of linear electron flow
- photon excites electron in pigment of light harvesting complex of PS2 boosting at a higher level drops giving energy to a neighbour pigment. Finally reaches P 60 pair of chlorophyl a and PS 2 Reaction Centre complex, excites into higher energy state
- P680 passes off electron is left oxidized as P680+
(Enzyme catalyzed water splitting: two electrons to hydrogen ions in an oxygen atom) - 680+ pear takes each electron, strongest oxidizing agent known in bio, The separate oxygen produced from two water molecules splitting combine to make O2
- electron transport chain between PSII and PSI, Electron carrier Pq (plastoquinone), sacrum complex, proteins Pc (plastocyanine): electron to drop in potential energy pumps hydrogen to eventually power ATP synthase
- light excites light harvesting complexes of PSI, P700 loses electrons to primary electron acceptor, P700+ draws electron from ECT
- PSII’s bottle excited electrons go through second ETC, use protein ferredoxin (Fd), no proton gradient no ATP made. Enzyme NADP+ reductase transfer e- fro Fd to NADPH (remove H+ from stroma too) (NADPH later use in Calvin cycle.
Explain cyclic electron flow
- photosystem one not two
- electrons cycle back from Fd to first cytochrome complex the back to P700 chlorophyll in reaction-center complex
- generates ATP in ETC, but no NADPH or O2
- evolutionary leftover, possibly photoprotective (low light good)
Explain how Kenya’s Moses powers ATP synthase
The electron transport chain harvested the potential energy from electrons and pumps hydrogen ions to create a gradient, the flow of hydrogen ions down the electrochemical gradient through ATP synthase create a loss of energy harvested by ADP to create ATP
What differs in the chemiosmosis of ATP synthase of mitochondria versus chloroplasts
- high E e- in chloroplasts come from water, mito come from oxidized organic molecules
- chloroplasts aren’t powered by food but by light energy
- chloroplasts: p+ thylakoids to stroma. Mito: intermembrane space to mito matrix
How would exposure to light affect the pH in the thylakoid space and stroma
Light: thylakoids pH drops (H+ increases) and stroma pH increases
No light: pH gradient abolished, balance restored
Why would it make sense that NADPH and ATP are produced on the side of the membrane place in the stroma
Because that’s where the Calvin cycle occurs, they are fuel for the Calvin cycle
What are the three phases of the Calvin cycle
- Carbon fixation: CO2 (one @ time) attached to RuBp (ribulose biphosphate) via Rubisco (enzyme carboxylase-oxygenase; most abundant protein on earth and in chloroplasts)—>6C unstable temporary intermediate—> 2 3-Phosphoglycerate (per 1 CO2
- Reduction
- ea 3-Phosphoglycerate gets P from ATP —> 3-Biphosphoglycerate
- gets pair of electrons (ea) from NADPH —> Glyceraldehyde 3-phosphate
(e- reduce a carboxyle grp to aldehyde group of 3-biphosphateg.)
**1 CO2=3 G3P(same sugar from cell res. Glycolysis)
3 CO2 = 1 net G3P (other 5 replenish 3 5C RuBp) - Regeneration - of CO2 acceptor RuBp
Spends 3 ATP to make 3 RuBp, using 5 G3P for 3 RuBp
Total usage (for 1 net G3P): 9ATP + 6 NADPH (made from light reactions) G3P synthesizes other oraganic molecules: 3 G3P=1 glucose *carbons go through the cycle one at a time, Calvin cycle does not make sugar
Where is ATP used in the Calvin cycle
The first step in the reduction phase, 3-phosphoglycerate receives phosphate from ATP. The regeneration of our RUBP from G3P.
How many carbon dioxide must run through the Calvin cycle for net one G3P
Three carbon dioxide
Which process creates sugars: light reactions or Calvin cycle
Neither, Calvin cycle creates G3 P molecules that are later synthesized to glucose
Which three molecules are a part of the reduction phase. Of the Calvin cycle
Three phosphoglycerate becomes three by phosphoglycerate becomes glyceraldehyde three phosphate, ATP and NADPH power reactions
What happens in the carbon fixation step of the Calvin cycle
RuBisCO catalyzes ribulose biphosphate (RuBp) into unstable temporary intermediate three phosphoglycerate
How is photorespiration a compromise to prevent dehydration
It’s a compromise between loss of photosynthesis and prevention of excessive water loss
What happens to see three plants in photo respiration
(C3 means first carbon fixation is three carbon compound)
Stomata partially close when hot and dry, less sugar made, less CO2 brought in, RuBisCO becomes promiscuous finding oxygen, creates to carbon compound in chloroplast, paroxysm and mitochondria split to release carbon, expense ATP
Why is photorespiration named as it is
Because it occurs in the light, consumes oxygen while producing CO2
What change is there in the amount of organic material during photo respiration as opposed to normal Calvin cycle functioning
Decrease in photosynthetic output by using organic material that would otherwise be able to make sugar
How does the evolution of photo respiration makes sense
Leftover relic when atmosphere had less O2 and more CO2
How does photo respiration protect the plant
From water loss and excessive light damage
In C4 plants, explain the preceding cycle that occurs in mesophyll cells before the Calvin cycle? How does lids cycle offer a leg up on hot and dry days?
- PEP carboxylase enzyme adds CO2 to phosphoenolpyruvate or PEP making 4C oxaloacetate
- 4C exported to bundle sheath cell through plasmodeta
- ruBisCO using 4C molecule regenerates pyruvate, then use ATP to convert pyruvate to PEP
PEP carboxylase higher affinity for CO2, no affinity for O2, works when hot and dry
*only cyclic electron PSI but PSII
Summary: mesophyll cells pump CO2 into bundle sheath, keep high CO2 concentration for RuBisCO to bind CO2 instead of O2
Where is ATP used in C4 plants? Where does this ATP come from?
When converting pyruvate to PEP.
Cyclic electron flow.
Why are increased levels of CO2 in the atmosphere and global warming a concern for C3 and C4 plants?
Increase for respiration, C3 power plants higher efficiency in more CO2. May alter population of C3 and C4 plants
How do you cam plants conduct photosynthesis?
Crassulacean acid metabolism,
Organic acid made and stored up at night
Stomata close in day, light reaction supply ATP and NADPH for Calvin cycle, CO2 released from organic acids
What is the name of the chlorophyl a of PII and PI
PII P680
PI P700
Where is ATP made in the light reactions of photosynthesis
Hydrogen gradient created by electron chain between P2 and PI, ATP synthase in thylakoid membrane
The second cycle complex after photosystem two is catalyzed by which enzymes, where does the energy go?
Fd (Ferredoxin) makes NADPH for Calvin cycle
How is water used in photosynthesis
Two waters make 102, electrons replenish P680+ of PII
Where does the plant get water for photosynthesis
From the roots transported by the veins to the leaves
What electron carriers are used in the first cytochrome complex after P2 of light reactions
Pq (plastoquinone) then Pc (plastocyanine)
How is P 700+ replenished after losing its electron
It draws in electrons from the cytochrome complex
What is carbolase-oxygenase
Rubisco
Compare the products of linear flow to cyclic flow
Linear flow: ATP NADPH and O2
Cyclic: ATP
