Chapter 10: Photosynthesis Flashcards
What are photons?
Discrete particles with a fixed amount of energy but no mass
What does the electron transport chain create in the light rxns?
Creates a buildup of H+ inside the cell which flow through ATP synthase to generate ATP
Where is chlorophyll found?
In the thylakoid membranes of the chloroplasts
What are the 3 phases of the Calvin cycle?
Carbon fixation, reduction, and regeneration of CO2 acceptor
What are C3 plants?
Plants that use rubisco for initial carbon fixation. Standard photosynthesis because a 3 carbon product is formed
Path of travel through the photosystems
Photosystem II to electron transport chain to photosystem I
How many tons carbohydrate are produced by a plant each year?
160 billion tons
What becomes oxidized in photosynthesis? What does it oxidized to?
H2O oxidized to O2
How do pigments act as protection?
Act as buffers to absorb excess energy from the sun so the plant isn’t damaged
What is white light?
Reflecting all visible light wavelengths
What is the range for the visible light spectrum?
380nm - 750 nm
What is it called when the cell generates ATP from the light rxns? What is it called when the equivalent happens in cellular respiration?
Photophosphorylation. Oxidative phosphorylation
Overview of regeneration of CO2 acceptor in Calvin cycle
Series of steps which utilize ATP to rearrange 5 molecules of G3P to regenerate 3 molecules of RuBP
What is the product of 3 rounds of the Calvin cycle?
6 G3P but only 1 net G3P
What types of plants have alternate methods of carbon fixation to minimize photorespiration?
C4 plants (4 carbon products) and CAM plants (crassulacean acid metabolism)
Where does the energy come from for photosynthesis?
Light
Light rxns equation
Light + H2O –> NADPH + ATP + O2
What do different pigments do?
Absorb different wavelengths of light
How do CAM plants work?
Stomata close during day to conserve H2O but open at night and take in CO2 and fix it in organic acids which are stored in vacuoles. During the day, CO2 is released from organic acids to enter the Calvin cycle with the supply of ATP and NADPH
Why do leaves change colors?
Presence of additional pigments like carotenoids. Plants stop producing chlorophyll when getting ready to lose leaves, so carotenoids are no longer masked
What occurs in the Calvin cycle?
Uses the chemical energy stored in ATP and NADPH to reduce CO2 to sugar (G3P)
What is chlorophyll a? What wavelength does it absorb?
Contains CH3. Absorbs highest around 430 nm
What does the z scheme mean in the photosystems?
Linear flow of electrons. They follow a z shape
What are granums?
Stacks of thylakoids in chloroplasts
What are the two parts of the photosystems that capture light in the light rxns?
Antenna complexes and run-center complexes
What do the light rxns do?
Convert light energy into chemical energy
What happens at the electron transport chain in the light rxns?
Electrons come with H+ from P680 in photosystem II into the electron transport chain. The electron transport chain provides energy for ATP synthesis by chemiosmosis. The electrons move into photosystem I
What do the light rxns do at the molecular level?
H2O split to provide electrons and H+, NADP+ reduced to NADPH, ATP produced, O2 given off
Overview of reduction in Calvin cycle
Carbon intermediate phosphorylated by ATP. Reduced by NADPH and loses the phosphate creating G3P
What are stomata?
A part of a plant that is an opening
What key step occurs in photosystem II?
H2O is split into O2 (which is a product) and H+ (electron)
What is light a form of?
Energy. Electromagnetic radiation