Photosynthesis And Electron Transport Lab Report

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Introduction: Investigating the effects of light intensity, NH4CL, and DCMU on the rate of electron transport in spinach thylakoid membranes was the purpose of this lab. Photosynthesis is the process that routinely drives electron transport across the thylakoid membrane but can be impacted when additional factors are added. Two phases known as the light reactions and the Calvin cycle makeup photosynthesis. Plastoquinone shuttle, water oxidation, and NADP+ reduction are the major factors of the light reactions. Photosynthesis creates a proton gradient when pigments in the thylakoid membrane absorb light energy from the sun. The energy is then used to oxidize water which is the initial electron donor, and NADP+ acts as the final electron acceptor. …show more content…
Light intensity was directly proportional to electron transport. As light intensity increased so did mean change in absorbance. The highest and lowest light intensities also had the highest and lowest mean change in absorbance. The more light that is readily available is a key factor in photosynthesis and electron transport. More light means more light energy which helps split water molecules at the beginning of electron transport. More light can split an abundance of water molecules which results in faster transport when electrons are needed because they are already available. Our hypothesis that DCMU will inhibit electron transport more than NH4CL was also confirmed. DCMU is an herbicide that inhibits electron transport between photosystemII and plastoquinone. Plastoquinone is the first agent that shuttles electrons but DCMU stops it from receiving the electrons. Since plastoquinone does not receive the electrons the transport of electrons is slowed down and less ATP and NADPH are produced. NH4CL is acted as an uncoupler in the lab. Uncouplers destroy the proton gradient and allow protons to pass freely bypassing ATPase. ATP production stops but electron transport continues. Since there is no gradient electrons move faster because there is less resistance due to ATP production being ceased. The information obtained from this lab is utilized in everyday life and we may not even n notice it. Uncoupling of NH4CL is the reason why animals dislike the smell of ammonia. It is also the reason NH4CL must be absorbed quickly into amino acids when used as a plant

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