Shmoop Editorial Team. The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. The function of the light-dependent reaction is to convert light energy into chemical energy within a multi-protein complex called the photosystem, found in the thylakoid membranes. The light-dependent reactions use ATP from the Calvin cycle, and the Calvin cycle uses energy from absorbed sunlight. today we will discuss the difference between light dependent and light independent reaction but before that let's first find out what is photosynthesis.based on what i researched photosynthesis is the process in which light energy is converted to chemical energy in the form of sugars. The Calvin cycle. This chemical energy will be used by the Calvin cycle to fuel the assembly of sugar molecules.     The light dependent reactions use photosynthetic pigments (organised into photosystems) to convert light energy into chemical energy (specifically ATP and NADPH)These reactions occur within specialised membrane discs within the chloroplast called thylakoids and involve three steps: Step 1:  Excitation of Photosystems by Light Energy, •  Excited electrons from Photosystem II are used to contribute to generate a proton gradient, •  ATP synthase in thylakoids generates ATP using the proton gradient,       Step 2:  Production of ATP via an Electron Transport Chain, •  Excited electrons from Photosystem I are used to reduce NADP, •  Photolysis of water generates electrons for use in the light dependent reactions,      Step 3:  Reduction of NADP+ and the Photolysis of Water, Overview of the Light Dependent Reactions. The light-dependent reactions take place in the thylakoid membrane, and the Calvin cycle takes place in the stroma. Photosystems I and II. The light-independent reaction also called the Calvin cycle is responsible for the generation of oxygen and glucose.It takes the reactants from the previous light-dependent reaction… Print. The Calvin cycle. Light Dependent Reactions Outline: - In the light-dependent reactions of photosynthesis, the energy from light propels the electrons from a photosystem into a high-energy state. The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. The light-dependent reactions Get 3 of 4 questions to level up! The process of photosynthesis is made up of light dependent reactions (the photo’ part) and sugar making or light independent reactions (the synthesis part). Match. The Calvin cycle converts water molecules into oxygen gas as a byproduct of its reactions. If the chlorophyll molecule is to continue absorbing light energy, these electrons must be replaced 3. The light-dependent reactions synthesise ATP and the reductant NADPH. When the light falls on the plant, the chlorophyll pigment absorbs this light and electrons in it … The light independent reactions occur in the fluid-filled space of the chloroplast called the stroma; The light independent reactions are collectively known as the Calvin cycle and involve three main steps: "The Light-Dependent and Light-Independent Reactions - Shmoop The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. The entire process occurs in three significant steps or stages. Step 2: Production of ATP via an Electron Transport Chain. The loss of electrons when light strikes a chlorophyll molecule leaves it short of electron 2. In the first step, i.e. In photosynthesis, the light-dependent reactions take place on the thylakoid membranes.The inside of the thylakoid membrane is called the lumen, and outside the thylakoid membrane is the stroma, where the light-independent reactions take place.The thylakoid membrane contains some integral membrane protein complexes that catalyze the light reactions. Light reactions harness energy from the sun to produce chemical bonds, ATP, and NADPH. The Light-Dependent Reaction 1. Print. Chlorophyll is the primary photosynthetic pigment; hence, thylakoid membranes are deep green in color. This short animation describes the light reactions of photosynthesis. The light dependent reaction happens when solar energy is captured to make a molecule called ATP (adenosine triphosphate). In PSII, energy from sunlight is used to split water, which releases two electrons, two hydrogen atoms, and one oxygen atom. Boston, MA: Pearson Prentice Hall, 2009. Light reaction is the first stage of photosynthesis process in which solar energy is converted into chemical energy in the form of ATP and NADPH. The basic steps of light-dependent reactions are: • Light absorption in Photosystem II (PSII) and excitation of PSII • ATP synthesiS-proton gradient in electron transport chain isdriving ATP production in a process of chemiosmosis The protein complexes and the pigment molecules help in the production of NADPH and ATP. Gravity. Light Dependent Reactions . In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and converted into stored chemical energy, in the form of the electron carrier molecule NADPH (nicotinamide adenine dinucleotide phosphate) and the energy currency … The light-dependent reactions begin in photosystem II. These energy-carrying molecules are made in the stroma where carbon fixation takes place. 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