IndexEnergy for processes in the organismLight-dependent production of ATP by an electron transport chainThe first step is carbon fixationStep 2 is the reduction of glycerated phosphateThe third stage is regeneration By RuBPTemperaturePhotosynthesis is the process described by this equation This equation shows the complex 2-step process that occurs in the chloroplast of green plants. The final product is not glucose, but the complex organic molecule such as carbohydrates, amino acids, lipids and nucleic acids. Photosynthesis is important because it is the biological process that produces > produces complex organic molecules necessary for growth. It produces oxygen which is used for respiration. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay Energy for Processes in the Organism When plants are eaten, organic molecules are used to provide energy to organisms higher up the food chain. The oxygen that is produced is released into the atmosphere and is available to other organisms.Structure of Chloroplast-Thylakoid: This is the second membrane that forms the envelope, chloroplast that contains a third internal membrane. The internal portion of the thylakoid is called the thylakoid lumen, it contains plastocyanin and other molecules necessary for electron transport. The thylakoid is a set of membranes stacked together and these stacks are called grama. Granum is a flat membrane that increases surface area and volume ratio, and small internal volumes rapidly accumulate ions. Intergranular thylakoid: Stroma - the stroma is an aqueous matrix present within the double membrane envelope. the internal components, as well as other solutes, are dispersed into the stroma. The stroma is rich in proteins and contains numerous enzymes necessary for cellular vital processes. Chloroplast DNA is also present in the stroma along with ribosomes and other molecules necessary for protein synthesis. Starch synthesized through photosynthesis is stored in the stoma in the form of granules. Photosynthetic pigments, this is a colored biological compound that is present in chloroplasts and photosynthetic bacteria and captures light energy for photosynthesis. In plants, the two types of pigments are chlorophylls and carotenoids. These are colored because they absorb particular wavelengths of light and reflect others. The reason plants are green is because of chlorophyll pigments, which give plants their green color by reflecting green light. Carotenoids reflect red, orange, or yellow light. ATP is an important molecule found in all living organisms. It diffuses around the cell and provides energy for cellular processes. Adenosine triphosphate is produced in the light-dependent reaction in photosynthesis from adenosine diphosphate and the organic phosphate group p and requires energy. ATP releases energy in the light-independent reaction and forms a bond between inorganic phosphate groups, which then produces ADP and an inorganic phosphate group. NADP and NADPH is the coenzyme involved in photosynthesis reactions. The compound is a nucleotide that contains an adenine base and a nicotinamide base. Nucleotides are joined through phosphate groups. There is an extra phosphate on the ribose of the adenine-containing nucleotide. NADP can accept electrons reduced to NADP, often called NADPH. This is oxidized back to NADP releasing electrons. In photosynthesis, the phosphorylation of ADP to form ATP uses the energy of sunlight and this is called photophosphorylation. There are only 2 sources of energy available to living organisms: sunlight and energyredox reactions of reduction and oxidation. All organisms produce ATP. There are two phases of photophosphorylation and these are Cyclic and Non-Cyclic Photophosphorylation. Steps of Photophosphorylation In the process of photosynthesis and phosphorylation of ADP to form ATP, this uses the energy of sunlight and this is called photophospy. The light energy of photophosphorylation is used to create a high-energy electron donor and a lower-energy electron acceptor. Cyclic photophosphorylation involves only photosystem 1 and does not utilize NADP+ reduction. When light is absorbed by photosystem 1, electrons will enter the electron transport chain to produce ATP. the de-energized electron will return to the photosystem restoring the supply of electrons. The electron will then return to NADP+, meaning it has not been reduced and water is not needed to replenish the electron supply. Noncyclic photophosphorylation is a two-step process involving two different photosystems. Photosystem II and photosystem I and requires NADP+ reduction. Non-cyclic occurs in the keys of the stroma. When light is absorbed by photosystem II, the electrons that have become excited will enter the electron transport chain to produce ATP while photoactivation of photosystem I causes the release of electrons that reduce NADH+ to form NADPH. Photolysis of water will release electrons which will then replace the electrons lost from photosystem II. Photolysis is the splitting of chemical compounds using light energy or photons. There are two steps to photosynthesis: this is light-dependent and light-independent. Light-dependent The light-dependent reaction uses photosynthetic pigments that are organized into photosystems that convert light energy into chemical energy, e.g. ATP and NADPH. The located membranes are light-harvesting systems called photosystems. There are 2 photosystems and these are Photosystem I and Photosystem II, both of which have chlorophyll at their core. The light-dependent photosynthesis reaction is the first important process in photosynthesis as it uses light energy which is then converted into chemical energy such as ATP and NADP. This occurs across the thylakoid membranes of the chloroplasts, between the chloroplast stroma and the thylakoid space. In thylakoids, there are 3 steps involved in the reaction that occurs in specialized membrane discs in the chloroplast and these are Excitation of photosystems by light energy. Production of ATP by an electron transport chain Reduction of NADP+ and photolysis of water The first step is Excitation of photosystems by light energy. This is when photosystems are transferred into clumps of photosynthetic pigments that include chlorophyll embedded in the thylakoid membrane. So the photosystems classified based on the maximum absorption wavelengths Photosystem I is equal to 700 nm and photosystem II is equal to 680 nm. When photosystems absorb light energy, the electrons delocalized in the pigments become energized or excited. Then these electrons that have been excited are transferred to carrier molecules in the thylakoid membrane. 2. The second stage of light dependence is the production of ATP by the electron transport chain. The electrons that existed from photosystem II P680 are transferred to an electron transport chain in the thylakoid membrane. Then, as the electrons pass through the chain, they lose their energy, which is then translocated into H+ ions in the thylakoid. This then accumulates protons in the thylakoid which creates an electrochemical gradient or proton driving force. H+ ions will return to the stroma along the proton gradient via chemiosmosisof the transmembrane enzyme ATP synthase ATP synthase uses the passage of H+ ions to catalyze the synthesis of ATP from ADP+Pi. This process is called photophosphorylation because light provided the initial energy source for the production of ATP. The de-energized electrons of Photosystem II will be absorbed by Photosystem I. 3. This is the last step of the Light Dependent. It is the reduction of NADP+ and photolysis of water. Electrons excited by Photosystem I can be transferred to a carrier molecule and used to reduce NADP+. This then forms NADPH, which is needed together with ATP for light-independent reactions. The electrons lost from photosystem I are replaced by de-energized electrons from photosystem II. Electrons lost from photosystem II are replaced by electrons released from water through photolysis. Water is split by light energy into H+ ions, which are used in chemiosmosis, and oxygen is released as a byproduct. Light-Independent Light-independent reactions use chemical energy derived from the light-dependent reaction to form organic molecules. In the light-independent reaction occurs in the stroma, this is the fluid-filled space of the chloroplast. The light-independent reaction is also known as the Calvin cycle and involves 3 phases: carboxylation of ribulose bisphosphate reduction of glycerate phosphate regeneration of ribulose bisphosphate The first step is carbon fixation The Calvin cycle is a chemical reaction that occurs in the chloroplast during photosynthesis. The cycle is a light-independent reaction because it requires sunlight, so it occurs after the energy has been captured from sunlight. The reaction begins when the 5C compound ribulose biphosphate (RuBP) An enzyme, RuBP carboxylase, catalyzes the attachment of the CO2 molecule to Rupp. This causes the 6C compound to be unstable and leads to the compound breaking into two 3C compounds called glycerate 3 phosphate GP. Then the cycle involves 3 molecules of RuBP combining with the 3 molecules of CO2 to form six molecules of GP2. Step 2 is the reduction of glycerate phosphate Glycerate 3 phosphate GP is converted to triose phosphate using NADPH and ATP The reduction of NADPH transfers hydrogen atoms to the compound, while the hydrolysis of ATP provides energy. So GP will need an NADPH and an ATP to form a triose phosphate. A single cycle will require six of each molecule. The third step is the regeneration of RuBP Of the six TP molecules produced per cycle, one TP molecule can be used to form half of a sugar molecule. 2 cycles will be needed to produce a single glucose monomer and more will be needed to produce polysaccharides such as starch. Ramininfg5 TP molecules will be combined with regenerated stocks of RuBP 5* 3C= 3*5C Regeneration of RuBP will require energy derived from the hydrolysis of ATP. Calvin Cycle Limiting Factors Affecting Photosynthesis The main factors affecting the rate of photosynthesis are light intensity, carbon dioxide concentration, and temperature. Light intensity Light intensity increases the rate of the light-independent reaction which increases photosynthesis, therefore the reaction is photoactivated. The more photons of light fall on the leaf, the more chlorophyll molecules are ionized and the more ATP and NADPH are generated. The light-dependent reaction uses light energy and is therefore not affected by temperature changes. When light intensity increases there are factors that limit the rate of photosynthesis. The rate will plateau as all available chlorophyll is saturated by light. Chlorophyll will be damaged when the rate drops.