Practical 2.docx - Practical 2 Title An experiment of...

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Practical 2 Title: An experiment of electron transport of isolated chloroplasts from silverbeet leaves using DCPIP dye and spectrophotometer at 600nm. Introduction: Photosynthesis is a process where plant produce glucose and oxygen from carbon dioxide and water by absorbing light energy. The glucose is then converted to pyruvate and gives out ATP by cellular respiration. Photosynthesis may occurs in two types of reactions which are light dependent and light independent reaction. During light dependent reaction, energy is absorbed in thylakoid membranes of chloroplast and transferred to the reaction centres (P680) of photosystem II (PS II). The energy absorbed enters is excited to higher energy level. The primary electron acceptor capture ¿ e ¿ and oxidised P680 and leave as + ¿ P 680 ¿ . This electron splits water by extracting 2e and release + ¿ 2 H ¿ and oxygen atom which then combine with another oxygen atom to form O 2 . Then, the electrons will pass through electron transport chain to photosystem I (PS I). When electron pass through cytochrome complex some proton will pumped into thylakoid lumen and used to form ATP from ADP via chemiosmosis. In PS I, electrons will be send to a short electron transport chain called protein ferredoxin (Fd). Then, it is used reduce + ¿ NADP ¿ to NADPH for light independent reaction. The aim of this experiment is to find out when chloroplast expose to different environment, how the rate of electron transport will be affected by measuring absorbance value using spectrophotometer.

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