Photosynthesis Flashcards
What is photosynthesis?
A process than converts Co2 and H2o to carbohydrates
What are phototrophs?
Photosynthetic organisms
Where is solar energy captured?
Int eh chemical form of ATP and NADPH
What are ATP and NADPH used to convert?
CO2 to hexose phosphates
Light dependent reactions…
- Are membrane bound
- Release O2 from splitting 2H2o molecules, with H+ from H2O used in the Chemiosmotic synthesis of ATP, and Hydride ion (H:-) from H2O reduces NADP+ to NADPH
Dark reactions…
Occur in solution, reduce gaseous CO2 to carbohydrate and require energy of NADPH and ATP
Chloroplast structure
Two surrounding membranes, internal membrane stacking
Chlorophylls are the…
Most abundant and important in light harvesting
What does chlorophyll contain?
A tetrapyrrole ring (chlorin) similar to heme but contains Mg2+
What do antenna pigments extend?
The range of light capture, especially in the green where chlorophyll absorbs poorly
What do antenna pigments and chlorophylls exchange?
Light energy (excited electrons) until captured
What are the two photosystems?
Photosystems I (PSI) and Photosystems II (PSII)
PSI and PSII
- Contain many proteins and pigments embedded in the thylakoid membrane
- Operate in series, connected by cytochrome bf complex
Electrons are conducted from?
H2o to NADP+
What do PSI and PSII both contain?
A reaction centre that is the site of the photochemical reaction. Chlorophylls in each relation centre are paired to capture light
What is PSI paired to capture?
P700, absorb light maximally at 800nm
What is PSII paired to capture?
P680, absorb light maximally at 680nm
What is the Z-scheme?
Path of electron flow and reduction potentials of the components in photosynthesis
What does the absorption of light energy convert?
P680 and P700 (poor reducing agents) to excited molecules (good reducing agents)
Mitchells chemiosmosis theory
Conversion of energy from electron transport via formation of a transmembrane electrochemical gradient
Photophosphorylation
Synthesis of ATP which is dependant upon light energy
Chloroplast ATP synthase consists of?
Two major particles, CF0 and CF1
Cyclic electron transport
Yields ATP but not NADPH, thus balancing the need for 3 ATP for every 2 NADPH
What does cyclic flow increase?
The protonmotive force and increases ATP production, but no NADP+ is produced
