Photosystem I have chlorophyll a molecule which takes in optimum light of 700 nm and is called P700, whereas the reaction center of photosystem II has P680, the form of chlorophyll a which takes in best the light of 680 nm. Photosystem I was discovered first. A Photosystem II splits water into 1/2 O2, H+, and e- . PS2 powers the pumping of H ions into the lumen of the cell. C. 6. This process is similar to the electron transport chain in the mitochondria of cells. Photosynthesis - Photosynthesis - Photosystems I and II: The structural and photochemical properties of the minimum particles capable of performing light reactions I and II have received much study. Later, photosystem II was discovered and found to be earlier in the electron transport chain. The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. The process of photosynthesis begins with energy from light being absorbed by photosystem II (PS2). Briefly describe the overall function of Photosystem II in the light-dependent reactions of photosynthesis. There are 2 photosystems, photosystem I (PS I) and photosystem II (PS II). The light-dependent reactions involve two photosystems called Photosystem I and Photosystem II.These photosystems include units called antenna complexes composed of chlorophyll molecules and accessory pigments located in the thylakoid membrane.Photosystem I contain chlorophyll a molecules called P700 because they have an … Isolated RC, named D1/D2 particles, contain 4–6 Chl a, 1 β-carotene and 1 or 2 cytochrome b 559 per two pheophytin a molecules (1).Polypeptides D1 and D2 exhibit marked homologies with the L and M subunits of the RC of purple bacteria, respectively (2). But it was too late, the name stuck. While at photosystem II and I, the electrons gather energy from sunlight. Photosystem I The light absorption processes associated with photosynthesis take place in large protein complexes known as photosystems. In photosystem II, the electron comes from the splitting of water, which releases oxygen as a waste product. Photosystems exist in the membranes of thylakoids. In the electromagnetic spectrum, the type of radiation that we call visible light occurs between _____. Chlorophyll can be found in _____. 5. State the reactants and the products for the light-dependent reactions. In photosystem I, the electron comes from the chloroplast electron transport chain. Photosystem I can be excited by light of wavelengths shorter than 700 nm, but photosystem II requires light of wavelengths shorter than 680 nm for excitation. Photosystem II (PSII) is a membrane protein complex which functions to catalyze light-induced water oxidation in oxygenic photosynthesis. Describe an antenna complex and state the function of the reaction center. Flow of Energy from Photosystem 2. 4. 2. Energized electrons from ____ enter an electron transport chain and are then used to reduce NADP+. Each photosystem is made of two components: 1) antenna complex that consists of 300-400 chlorophyll a and b molecules and other accessory pigments such as carotenoids and 2) reaction center that consists of one or more chlorophyll molecules with a primary electron acceptor. Both photosystems must operate for the chloroplast to produce NADPH, ATP, and O 2 , because the two photosystems are connected by the electron transport chain. Abstract. The Electron Transport Chain. Photosystem II reaction centers (RC) consist of D1 and D2 polypeptides and a bound cytochrome b 559. A pigment molecule in the photosystem absorbs one photon, a quantity or “packet” of light energy, at a time. These are called so in order of their discovery. Electrons first travel through photosystem II and then photosystem I. A & C. 7. 3. A photon of light energy travels until it reaches a molecule of chlorophyll. The one known as Photosystem I contains a chlorophyll dimer with an absorption peak at 700 nm known as P700.. Photosystem I makes use of an antenna complex to collect light energy for the second stage of non-cyclic electron transport. Treatment of lamellar fragments with neutral detergents releases these particles, designated photosystem I and photosystem II, respectively. 6 O 2 + 12 NADPH + 18 ATP. 5.