Light Dependent And Independent Reactions

Light intensity is a key component in photosynthesis, amongst carbon dioxide and water to sustain a suitable rate of photosynthesis. Chlorophyll absorbs the light, causing photoexcitation and the formation of NADPH and ATP with production of O2 as a by-product. The Calvin Cycle takes the NADPH and ATP to reduce CO2 into sugars (CH2O), and return NADP+ and ADP + Pi to the light reactions. The process will then repeat. (Reece, et al, 2015)

The light reactions also generate ATP by using chemiosmosis through a process called photosphorylation. The light energy is converted into chemical energy in the form of two compounds, which are NADPH and ATP. The Calvin cycle occurs with the incorporation of carbon dioxide into organic molecules in carbon fixation. In this process, the fixed carbon is reduced with electrons provided by NADPH. The Calvin cycle takes place during daylight hours, in which the NADPH and ATP can be provided. The Calvin cycle occurs in the stroma, while the light reactions occur in the thylakoids.

L. Relate the functions of the antenna complex and the reaction center in a chloroplast

The rate of photosynthesis can be determined different ways. Because oxygen is a product of photosynthesis and the Elodea plant is submerged in water, the oxygen is released in bubbles that rise to the surface of the water in the beaker. In this experiment, the rate of photosynthesis for each degree of light intensity can be measured by counting the number of bubbles released every 30 seconds for five minutes at each distance. The rate is the number of bubbles released per minute.

The process of photosynthesis, by which light energy is used to convert inorganic compounds into organic substances with the release of oxygen, may be the most important biological event sustaining life (Keir et al. 2017). In the light-dependent reactions, the chloroplasts of a plant use the pigment chlorophyll to convert light energy into chemical energy. This energy is used to split water and produce oxygen (Eller et al. 2015). The energy is later used in the light independent reactions, where carbon dioxide (CO2) undergoes carbon fixation with the aid of enzyme rubisco, because it catalyses both carboxylation and oxygenation reactions and most of responses of photosynthesis to light, CO2, and temperature (John Evans 2013).

The Calvin cycle is also known as the “dark reactions” or the “light independent reactions”. In the light reactions, energy from sunlight is captured, and stored in ATP and NADPH. These are then passed on to the Calvin cycle.

In light reactions, light is absorbed by chlorophyll in the thylakoid membrane and energizes the electrons. ATP is created from ADP and P. NADP accepts electrons and turns in to NADPH, which is energy. Once the light reactions have taken place, the light-independent, or ‘dark’ reaction occurs in the stroma, where CO2 is converted to sugar. The

This can be backed up by Miller and Levine’s Biology textbook. They explained, “Light-dependent reactions require the direct involvement of light and light-absorbing pigments,” (Miller & Levine, 233). “The light-independent reactions carbon dioxide from the atmosphere and complete the process of photosynthesis,”

The Calvin cycle refers to the light-independent reactions in photosynthesis that take place in three key steps. Although the Calvin Cycle is not directly dependent on light, it is indirectly dependent on light since the necessary energy carriers (ATP and NADPH) are products of light-dependent reactions.

ATP and NADPH are produced in light dependent reactions. These products are used to fuel

This light is then converted into a chemical energy by the chlorophyll and other pigments within the plant. This energy is used for the process of photosynthesis. During photosynthesis, water molecules split apart, releasing electrons and hydrogen ions and producing oxygen gas. These electrons and hydrogen ions are then used to generate ATP and NADPH. Both ATP and NADPH are also used in the light independent reaction, which is the second part of photosynthesis. This reaction occurs in the stroma of the chloroplasts. In contrast to the light dependent reaction, this type of reaction can occur without light. During the light independent reactions of photosynthesis ATP and NADPH are required to form glucose. Adenosine triphosphate, often called ATP, is used to construct organic molecules from carbon dioxide and water. Nicotinamide adenine dinucleotide phosphate, often called NADPH, reduces carbon dioxide and produces monosaccharides for use by the plant.

This is known as the light dependent reaction of photosynthesis. The goal of photophosphorylation is to take the energy from sunlight and convert it into chemical energy for the Calvin cycle. The Calvin cycle then takes this chemical energy and uses it to make glucose. Photophosphorylation begins when a photon (packet of light) is absorbed by a pigment (light absorbing molecule), which is attached to a protein along the thylakoid membrane of the chloroplast. The energy from the photon creates resonance (electron passing from one pigment to the next), which eventually reaches a special reaction center. The reactions center is a protein that houses a special pair of chlorophyll molecules capable of releasing electrons. When the chlorophyll molecules get excited, they release two electrons. These two electrons then move along the membrane through a series of specialized protein releasing energy as they go. This action creates an H+ gradient inside the lumen of the chloroplast. Eventually the electrons reach the end of the chain and attach onto electron carriers. The H+ flow across the ATP Synthase protein where they meet up with ADP (andesine diphosphate) and Pi (phosphate group) to from ATP. The chemical energy created can then be used in the Calvin

The main source of energy in photosynthesis is light energy, which is converted to glucose sugar, and later converted into ATP to provide energy to the cells. In the first phase, photons of sunlight hit the thylakoid membrane, exciting chloroplast molecules, inducing the transport of the electrons extracted from water splitting to form oxygen, down an electron transport chain, much like the one in cellular respiration. In this electron transport chain, the final electron acceptor is NADP+, which is reduced to NADPH to be used later in the Calvin cycle. Much like in cellular respiration, a proton gradient builds up within the thylakoid, and protons are passively transported from the thylakoid lumen to the chloroplast stroma through the enzyme, ATP synthase which phosphorylates ADP to make ATP. This type of chemiosmosis of protons to create ATP energy is uniquely called photophosphorylation. In photosynthesis, carbon dioxide is taken up from the atmosphere from the plants’ stomata, ultimately to create glucose molecules. The oxygen released from water splitting by photosystem II is crucial for almost all life. Overall, the process of photosynthesis is anabolic, as it builds up a large molecule, glucose from less complex smaller molecules, while requiring energy to do so.

     Photosynthesis has a two-stage performance before plants produce the two products they are known to produce. These stages are Photosystem I and II. Photosystem II is dependant on light reactions for energy which causes the electrons to be react and be transferred to Photosystem II. The electrons are transported through the Photosystem II electron transport system, however some energy is used to drive ATP synthesis. Meanwhile, light is being absorbed by the Photosystem I, which causes the electrons to react. This process sends the electrons to the Photosystem I transport system where some energy is released as electrons travel through the electron transport system and is captured as NADPH. When this process is completed oxygen is released from the plant and glucose has been

     In photosynthesis, the dark reactions are chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions unlike light-dependent reactions do not need light to occur. These reactions take the products of the light-dependent reactions and perform further chemical processes on