Leaves contain chloroplasts, in which photosynthesis occurs.
Without chloroplasts, the plant cells would no longer be able to carry out the process of photosynthesis.
the ATP needed for photosynthesis is produced in the mitochondria
For each electron flowing from water to NADP+ (a net change in1.14 volts), two quanta of light are absorbed, one by eachPhotosystem. Each molecule of oxygen released involves the flowof four electrons from two water molecules to two NADP+s andrequires four quanta of sunlight absorbed by each Photosystem toprovide the energy to do this. These are the "Light PhaseReactions" of photosynthesis, which produce two high energychemical products, namely NADPH and ATP.
Photophosphorylation is the production of ATP using the energy of sunlight. Photophosphorylation is made possible as a result of chemiosmosis. Chemiosmosis is the movement of ions across a selectively permeable membrane, down their concentration gradient. During photosynthesis, light is absorbed by chlorophyll molecules. Electrons within these molecules are then raised to a higher energy state. These electrons then travel through Photosystem II, a chain of electron carriers and Photosystem I. As the electrons travel through the chain of electron carriers, they release energy. This energy is used to pump hydrogen ions across the thylakoid membrane and into the space within the thylakoid. A concentration gradient of hydrogen ions forms within this space. These then move back across the thylakoid membrane, down their concentration gradient through ATP synthase. ATP synthase uses the energy released from the movement of hydrogen ions down their concentration gradient to synthesise ATP from ADP and inorganic phosphate.
ATP synthase, photosynthesis Flashcards | Quizlet
So how can these factors have an effect on the rate of photosynthesis? Lets start off with the light intensity. When the light intensity is poor, there is a shortage of ATP and NADPH, as these are products from the light dependent reactions. Without these products the light independent reactions can't occur as glycerate 3-phosphate cannot be reduced. Therefore a shortage of these products will limit the rate of photosynthesis. When the carbon dioxide concentration is low, the amount of glycerate 3-phosphate produced is limited as carbon dioxide is needed for its production and therefore the rate of photosynthesis is affected. Finally, many enzymes are involved during the process of photosynthesis. At low temperatures these enzymes work slower. At high temperatures the enzymes no longer work effectively. This affects the rate of the reactions in the Calvin cycle and therefore the rate of photosynthesis will be affected.
Photoaututrophs utilize sunlight for energy and CO2 for theircarbon source by this process of PHOTOSYNTHESIS whereby sunlightis absorbed by a complex compound known as chlorophyll andconverted to energy which drives a series of chemical reactionsthat ultimately removes hydrogen from water or other compoundsand then combines the hydrogen with carbon dioxide in a way thatproduces sugars.
ATP and Photosynthesis Flashcards | Quizlet
If the light intensity is not a limiting factor, there will usually be a shortage of NADP+ as NADPH accumulates within the stroma (see light independent reaction). NADP+ is needed for the normal flow of electrons in the thylakoid membranes as it is the final electron acceptor. If NADP+ is not available then the normal flow of electrons is inhibited. However, there is an alternative pathway for ATP production in this case and it is called cyclic photophosphorylation. It begins with Photosystem I absorbing light and becoming photoactivated. The excited electrons from Photosystem I are then passed on to a chain of electron carriers between Photosystem I and II. These electrons travel along the chain of carriers back to Photosystem I and as they do so they cause the pumping of protons across the thylakoid membrane and therefore create a proton gradient. As explained previously, the protons move back across the thylakoid membrane through ATP synthase and as they do so, ATP is produced. Therefore, ATP can be produced even when there is a shortage of NADP+.
The light-independant reactions of photosynthesis occur in the stroma of the chloroplast and involve the conversion of carbon dioxide and other compounds into glucose. The light-independent reactions can be split into three stages, these are carbon fixation, the reduction reactions and finally the regeneration of ribulose bisphosphate. Collectively these stages are known as the Calvin Cycle.
where in the chloroplast is ATP produced? | Yahoo …
chloroplast | Function, Location, & Diagram | …
Chloroplast: Chloroplast, structure within the cells of plants and green algae that is the site of photosynthesis.
photosynthesis Study Sets and Flashcards | Quizlet
Chemiosmosis and ATP synthesis
ATP and Energy Storage - Biology in Motion
We now shift our attention to photosynthesis, the second main process for synthesizing ATP
Photosynthesis: Crash Course Biology #8 - YouTube
Plant photosynthesis, both the Light Phase and Dark phasereactions, takes place in chloroplasts, which may be regarded asthe "power plants" of the green leaf cells. At night,when there is no sunlight energy, ATP continues to be generatedfor the plant's needs by respiration, i.e., oxidation of(photosynthetically produced) carbohydrate in mitochondria(similar to animals).
This tutorial introduces plant chloroplasts
Chloroplasts have many shapes in different species but aregenerally fusiform shaped (and much larger than mitochondria) andhave many flattened membrane-surrounded vesicles called thylakoidswhich are arranged in stacks called grana. Thesethylakoid membranes contain all of the photosynthetic pigments ofthe chloroplast and all of the enzymes required for Light Phasereactions. The fluid in the stroma surrounding the thylakoidvesicles contains most of the enzymes for Dark phase reactions.
Chemistry for Biologists: Photosynthesis
So we can summarize by saying that the photosynthetic plantstrap solar energy to form ATP and NADPH (Light Phase) and thenuse these as the energy source to make carbohydrates and otherbiomolecules from carbon dioxide and water (Dark Phase),simultaneously releasing oxygen in to the atmosphere. Thechemoheterotrophic animals reverse this process by using theoxygen to degrade the energy-rich organic products ofphotosynthesis to CO2 and water in order to generate ATP fortheir own synthesis of biomolecules.
This tutorial introduces photosynthesis
Photosynthesis converts these energy- depleted compounds (ADPand NADP+) back to the high energy forms (ATP and NADPH) and theenergy thus produced in this chemical form is utilized to drivethe chemical reactions necessary for synthesis of sugars andother carbon containing compounds (e.g., proteins, fats). Theproduction of high energy ATP and NADPH in plants occurs in whatis known as Light Phase Reactions (Z Scheme) (requiressunlight). The energy releasing reactions which converts themback to energy-depleted ADP and NADP is known as Dark PhaseReactions (Calvin Cycle) (does not require light) in whichthe synthesis of glucose and other carbohydrates occurs.
Photosynthesis Quiz - Science Geek
The oxidative chemical reactions of respiration releaseenergy, some of which is heat and some of it is captured in theform of high energy compunds such as Adenosine triphosphate (ATP)and Nicotinamide adenide dinucleotide phosphate (NADPH). Thesecompounds have a high energy (unstable) terminal phosphate bondand that terminal phosphate is easily detached with the transferof the energy to drive chemical reactions in the synthesis ofother biomolecules. In this case, the ATP loses one phosphate tobecome the energy-depleted ADP (Adenosine diphosphate)and the NADPH loses one electron to become energy-depleted NADP+.
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