HL CONTENT BRUH

• Light is absorbed by photosystems (II/I) chlorophyll - photosystems are arrays of pigment molecules and LHC • Energy is passed along to a reaction ceneter and electrons are excited / photoactivated • Photolysis of water splits water into H, O2, and E • E from photolysis replace the e lost in PS II, o2 is released as waste product • ATP produced y chemiosmosis in the thylakoid membranes - E paased along e carrier molecules (in thylakoid) - Protons are pumped from stroma into thylakoid lumen - proton gradien is formed - protons diffuse through ATP synthase to form ATP by photophosphorylation - ADP + pi –> ATP • E from PS II are passed to PS I • Light energy is absorbed by PS I and e are photoactivated • 2 E are paased to NADP+ which is reduced as it accepts 2 e, 2 h to form NADPH (reduced NADP) • Non-cyclic photophosphorylation produces ATP and NADPH in light dependent reactions.

Photosystems are located in thylakoid membra nes in chloroplasts of photosynthetic eukaryotes and in membranes of cyanobacteria Photosystems are arrays of pigment molecules and LHC’s with a special chlorohyll as the reaction center Chlorophyll / PSI, PSII absorb light energy, where energy is passed along until it reaches a reaction center where electrons are photoactivated.

Structured array of pigments allows for light energy to be absorbed and transferred to the reaction center in a controlled way Accessory pigments allows for a wider range of wavelengths to be absorbed Hundreds of pigment molecules allows for more energy to be absorbed and photoactivation to occur Electron carrier molecules allow for the efficient transfer of energy

Splitting of water in PSII using light energy * occurs only in PSII / non-cyclic photophosphorylation Photolysis splits water into H,O,E * E replace the e lost in PSII * H used to generate proton gradient and reduce NADP * O2 released as byproduct

Chemiosmosis is the coupling of electron movement to proton gradient formation and the synthesis of ATP • E- photoactivated in PS II are passed through a series of E- carriers in they thylakoid membrane • Movement of E- releases energy and is used to PUMP H from the stroma into the thylakoid lumen • Proton gradient formed • Protons diffuse through ATP synthase and the movement of protons from the thylakoid lumen to the stroma generated ATP by photophosphorylation • non-cyclic photophosphorylation, ATP being produced by PS II

ATP produced by PSI - only in bacteria - only invovles PS I - only produce ATP - E- excited in PS I returns to PS I

Light energy is absorbed by chlorophyll / PS I and e- are photoactivated E- from PS II are passed to PS I and replace the E- that were photoactivated E- are passed to NADP+ which is reduced to form NADPH as it accepts H from the stroma and 2 E-

Light dependent reactions occur along the thylakooid membrane where: * Photolysis of water * Synthesis of ATP by chemiosmosis * Reduction of NADP occur

Fix carbon dioxide occur in the stroma glycerate 3-phosphatae is the first identifiable product

Rubisco is the most abundant enzyme on earth - high concentrations of Rubisco are needed in the stroma of chloroplasts beacuse it works relatively slowly and not effecitve in low co2 concentrations

RUBP is a 5 carbon compound * RUBISCO fixed co2 to RuBP to form an unstable 6 carbon compound whihc breaks down to form 2 molecules of Glycerate 3-phosphate

G3P converted into triose phosphatase usng ATP and NADPH from the light dependent reactions Glycerate 3-phosphate is phosphorylated by ATP - ATP provides energy G3P reduced by NADPH to form a triose phosphatse

RUIBP is regenerate from triose phosphatase using the energy provided by ATP 5 molecules of PGA (3c) are equal to 3 molecules of RUBP

Formation of glucose 2 Triose phosphatase are shuttled out to produce glucose, - Glucose is the substrate through which other carbon compounds are formed by metabolic pathways - All carbon in compounds in photosynthesizing organisms is from the calvin cycle.