Week 4 Slides Flashcards
Photosynthesis equation
6CO2 + 6H2O —(light)—-> C6H12O6 + 6O2
Plants absorb light how?
By wavelength (energy of light is in photons)
What is the visible spectrum
400nm-700nm
Plants absorb light through…
Pigments (they absorb light based on specific wavelength)
Chlorophyll a
All plants have them
Needed to split water
Accounts for 75 percent of all pigments
Accessory pigments
Other pigments besides chlorophyll a
Absorbs light and transfers energy to chlorophyll a
Accounts for 25 percent of all pigments
Name some accessory pigments
Chlorophyll b, carotenoids, chlorophyll C (brown algae and diatoms), phycobilins (Cyanobacteria), xanthophyll, anthocyanin
All the locations of pigments
Leaf tissue, mesophyll cells, parenchyma cells, in chloroplasts, thylakoid membranes
Stack of thylakoids is called
Granum
Main things that happen in light dependent reaction
- happens in thylakoid membranes (pigments)
- pigments capture light and energy is used to split water into protons, electrons, and oxygen
- NADPH and ATP are byproducts
In light reaction what powers ATP synthase
The proton concentration gradient across the thylakoid membrane and lumen
Explain PS1 and PS2
PS1: happens second, uses electrons to produce NADPH; happens at 700nm
PS2: happens first, splits water to generate protons; happens at 680nm
All important things about the light independent reaction (Calvin cycle or carbon fixing)
-happens in stroma (fluid portion of chloroplast)
-CO2 enters through leaf storages and is fixed into organic form, GA3P, or PGAL (glyceraldehyde 3-phosphate) leaving stroma and entering Cytosol of cell
-enzyme us rubisco or RuBP carboxylase/oxygenase
Light reaction reactants and products
Reactants: water, ADP, NADP+
Products: protons, electrons, NADPH, ATP, O2
Calvin cycle products and reactants
Reactants: NADPH, ATP, CO2
Products: ADP, NADP+, 3 carbon sugar
3 carbon sugar product of Calvin cycle is usually made into what
Glucose (polymer of starch stored in cells)
Sucrose (fructose+glucose) found in cytoplasm
C3 plants
Use Rubisco for Calvin cycle (all plants)
In mesophyl only
C4 plants
-enzyme is PEP carboxylase (fixes carbons into oxaloacetate in mesophyll cells, then converted into malate or Aspartate)
-malate and Aspartate then go to bundle sheath cells in chloroplast, they are converted back into CO2 and pyruvate to enter Calvin cycle
-once in bundle sheath cells rubisco is enzyme used
-these plants are found in hot areas
-more efficient because PEP carboxylase does not bind to oxygen
CAM plants
Crassulacean acid metabolism
-temporal rather than spatial seperation (C4) of carbon fixation
-occurs in mesophyll cells only
-night time it takes in CO2, day time they use Calvin cycle with rubisco as enzyme
-stomates open at night only to reduce water loss
-malic acid made at night and stored in vacuole to wait for day
-PEP carboxylase is used at night
-slow growing plants
