The light reaction occurs in two photosystems (units of chlorophyll molecules). In (b) photosystem I, the electron comes from the chloroplast electron transport chain discussed below. Chlorophyll is the pigment involved in capturing light energy. Where is chlorophyll a found. The electrons of photosystem 1 go down an electron transport chain (protein ferredoxin) were the reach the enzyme NADP+ reductase. During photosynthesis, an electron transport chain is used to _____. 2) Uses FERREDOXIN-LIKE IRON-SULFUR cluster proteins as terminal electron acceptors. Cyclic Electron Transport in Photosynthesis Photophosphorylation refers to the use of light energy to ultimately provide the energy to convert ADP to ATP, thus replenishing the universal energy currency in living things.In the simplest systems in prokaryotes, photosynthesis is used just for the production of energy, and not for the building of any biological molecules. What is Electron Transport Chain in Chloroplasts? Ferredoxin transfer an electron to NADP+. in P680 and P700 reaction center. Explanation: Two photosystems, photosystem I and photosystem II, are protein complexes which absorb radiant energy. In the model, the electron transport chain comprises photosystem 2, plastoquinone, cytochrome b/f, plastocyanin, photosystem 1, ferredoxin and NADPH. Photosystem I (PS I) and photosystem II (PS II) are two multi-subunit membrane-protein complexes involved in oxygenic photosynthesis. The movement of electrons down the electron transport chain drives the formation of a protons gradient that is used to make ATP. Photosystem II splits water into oxygen atoms, hydrogen protons that remain in the thylakoid lumen, and hydrogen-derived electrons that move from the reaction center into the electron transport chain. Ratings 100% (1) 1 out of 1 people found this document helpful This preview shows page 7 - 15 out of 26 pages. As in Photosystem II, light is harvested by antenna complexes, and the primary light reaction is a charge separation beginning stabilized by transfer of an electron to a quinone, but in Photosystem I the terminal electron acceptor is an FeS cluster, which permits reduction of ferredoxin. Carbon metabolism is described in detail. Photosystem I (PS I) 3. Oxygen continuously diffuses into plants; in animals, it enters the body through the respiratory system. When an electron reaches the “bottom” of the electron transport chain, it fills an electron “hole” in the chlorophyll a molecule in the reaction center of photosystem I (P700). transport electrons from photosystem II to photosystem I 20 Which of the following is cycled in the cyclic variation of the light reactions? When photosystem II absorbs light, electrons in the reaction-center chlorophyll are excited to a higher energy level and are trapped by the primary electron acceptors. Photosystem II (PS II) 2. After the absorption of light in photosystem II, the electrons travel and transfer to photosystem I. If the only organisms on Earth that perform photosynthesis were bacteria w/ only 1 photosystem, would the resulting environment be capable of supporting animal life? what photosystem does cyclic flow use. That biological reducing agent, closely related to NADH, will be used to help reduce carbon dioxide. Photoexcited electrons travel to photosystem I through an electron transport chain set in the thylakoid membrane. Since the energy source is sunlight, the phosphorylation of ADP to ATP is known as photophosphorylation. This energy is used to create an electron transport chain. Even with one photosystem, the electron transport chain would still be able to pump out protons from the thylakoid space into the stroma, forming a proton gradient. ; Electrons are passed along the chain from protein complex to protein complex until they are donated to oxygen. p700. how is ATP made. The electrons undergo a series of reactions as they are transferred from one protein to another in an electron transport chain.The light-dependent reactions break down water molecules, separating into hydrogen ions, oxygen molecules and electrons. Electron transport chain which takes place inside the chloroplast is commonly known as photophosphorylation. The four electrons removed from the water molecules are transferred by an electron transport chain which is formed hydrogen ions and molecular oxygen to plastoquinone2. Second, the cyclic pathway makes use of only one photosystem and one electron transport chain. The electron transport chain is a cluster of proteins that transfer electrons through a membrane within mitochondria to form a gradient of protons that drives the creation of adenosine triphosphate (ATP). In a first version, low-molecular carriers are assumed to be freely diffusible. 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