The process of photosynthesis is composed of two phases: light-dependent reactions and the Calvin cycle. The first stage (light-dependent reactions) occurs in the thylakoid membrane, which absorbs light energy to create NADPH and a proton gradient used to power the synthesis of ATP. The latter occurs in the stroma, and results in carbon dioxide fixation. In this experiment, only the light-dependent reactions were studied.
2,6-dichlorophenol-indophenol (DCPIP) was used as an artificial electron acceptor in order to determine the rate of the light reactions by observing the disappearance of its blue color in the reaction that follows: DCPIP (blue) + 2e- + 2H+ → DCPIPH2 (colorless)
In one experiment, ammonia, which is added in the form of ammonium chloride, is used as an uncoupler and destroys the pH gradient by lowering the pH outside the thylakoid membrane with the release of protons. In another, the herbicide dichlorophenyl-dimethylurea (DCMU) is added to inhibit the transport of electrons between PSII and plastoquinone (Monroe, 2015).
In the experiment testing light intensity, it was predicted that an increase in light …show more content…
The same procedure was used to create the solutions in this experiment with the addition of 700ul of the desired treatment added to each of the tests. Three trials were done for each treatment. Water was also used. Water became a control to compare against the DCMU and NH4Cl . Each test used the same light intensity and was exposed to the light for 110 seconds. Absorption was also measured before and after each test at 600nm in the spectrophotometer. Average change in absorption of the thylakoid membrane was calculated. A relationship was displayed between the absorption and the treatment type by the use of a bar graph. Error bars were used and calculated by the use of the standard
2,6-dichlorophenol-indophenol (DCPIP) was used as an artificial electron acceptor in order to determine the rate of the light reactions by observing the disappearance of its blue color in the reaction that follows: DCPIP (blue) + 2e- + 2H+ → DCPIPH2 (colorless)
In one experiment, ammonia, which is added in the form of ammonium chloride, is used as an uncoupler and destroys the pH gradient by lowering the pH outside the thylakoid membrane with the release of protons. In another, the herbicide dichlorophenyl-dimethylurea (DCMU) is added to inhibit the transport of electrons between PSII and plastoquinone (Monroe, 2015).
In the experiment testing light intensity, it was predicted that an increase in light …show more content…
The same procedure was used to create the solutions in this experiment with the addition of 700ul of the desired treatment added to each of the tests. Three trials were done for each treatment. Water was also used. Water became a control to compare against the DCMU and NH4Cl . Each test used the same light intensity and was exposed to the light for 110 seconds. Absorption was also measured before and after each test at 600nm in the spectrophotometer. Average change in absorption of the thylakoid membrane was calculated. A relationship was displayed between the absorption and the treatment type by the use of a bar graph. Error bars were used and calculated by the use of the standard