Photosynthesis Lab

Photosynthesis is a process done in the chloroplasts of plant cells that is beneficial to all of life. Plants are able to convert light to energy which is beneficial to the plants, while also giving off oxygen as a byproduct for humans. Chloroplasts are in the thylakoid discs of a plant cell, that contain chlorophyll a and chlorophyll b, which are it’s light-capturing pigments. Colors in the wavelengths are either absorbed or reflected by the chlorophyll in which case green is reflected and colors like red and blue are seemed to be absorbed. If blue and red wavelengths have more absorbance, the green doesn’t have a high absorbance. This lab is useful to help demonstrate the existence of various leaf pigments by using the process of paper chromatography.
A spectrophotometric scan of extracted leaf pigments will then be used to affirm the wavelengths of light absorbed, then compared to the absorption spectrum of chlorophylls. After partaking in this lab you will cover many objectives such as being able to distinguish the major structures of a leaf, being able to record the major pigments that give a leaf it’s color and it’s ability to trap light, and be able to explain how chlorophyll a and b take a big role in photosynthesis. Thus knowing all of this general knowledge, you will be able to apply it to understand how paper chromatography is used to separate and aid in the classification of multiple leaf pigments. Also, you will able to explain the absorption curve in the visible light wavelengths that will be exhibited by spectrophotometric analysis of leaf extracts. Does chlorophyll absorb most light in the blue and red
Using a pencil, you must make a line about 2cm from the end, this will be the beginning point. Then, you will take the leaf sample, place it on the filter paper, and start rolling a coin amongst the leaf along the penciled baseline. The more you roll the coin, the more of a concentration of the pigments will be visible, eventually you will see a dark green line. Your instructor will have a control chromatogram (only solvent) ready and you will check to make sure you left enough room below the sample line in order to make sure the sample isn’t submerged in the solvent. Under the fume hood, the chromatography solvent (90% petroleum ether: 10% acetone) will be added to the tube, approximately 2 ml is enough. The paper is then placed in the solvent, while making sure the sample line is above the solvent and dry. You will then cover the top of the tube with Parafilm and set it aside. At about 30 minutes, the climbing solvent front will have proceed 6-7cm from the beginning point. You can then remove the paper strip from the tube and mark the solvent front with a pencil