Plant Pigments

Name: Maggie Lou M. Gubalane    BAS-1                        Subject: Botany 11(Laboratory)

Schedule:  Friday, 7:00-10:00                        Instructor: Kenneth Eco

EXERCISE NO. 1

Plant Pigments

I. Introduction

              Pigments are molecules that absorb the visible light. Because of this, plants and animals have their unique colors. In plants, the major function of pigment is photosynthesis. Those pigments that do not function for photosynthesis are called accessory pigments or non-photosynthetic pigments. The primary functions of these pigments are the indication of maturity and provision of color which is essential for attracting pollinators.

               The most common non-photosynthetic pigments are the anthocyanins, betalains and carotenoids. Anthocyanins are water soluble pigments that appear red to blue, according to pH and they are located inside the central vacuoles of plant cells. Betalains are red or yellow pigments and it is also water soluble. Unlike anthocyanins, betalains are only found in the Caryophylles, and never found in the same plants with anthocyanins. They are somewhat related before but it is no longer true for the two can be distinguished by color responses to pH changes.  Carotenoids are red, orange or yellow pigments that act as accessory pigments to chlorophyll during photosynthesis. They are not soluble in water, thus they are found in the cell membrane of plant cells.

II. Objectives

• To distinguish hydrophobic and hydrophilic pigments
• To distinguish anthocyanins and betalains based on their reactions on various alkalinity and acidity
• To observe the location of plant pigments in the cell.

III. Methods

                The experiment was divided into three parts. The first part was the determination of chemical property. Second was the determination of the effect on pH on pigment color and the third part was the determination of pigment location of the cell.

            On the first part, extracts were collected using the three subjects; tomato fruit (Lycopersicom esculentu), pigweed stem (Portulaca oleracea ) and purple heart leaves(Setcreasea purpurea ) were put into the blender separately and was added with 50mL acetone water and let it homogenized. Afterwards a filtration set-up was made to separate the filtrate from the residue. When the filtrate was collected from each of the three subjects, it was transferred to a separatory funnel. It was added with 20mL petroleum ether and was set aside for 5-10 minutes. In part 2, the extracts from part 1 was put into five test tubes labeled from T0-T4. Each test tube was added with 2mL of the following treatment solutions of varying pH level: T0- distilled water, T1- 0.1M HCl, T2- 0.01M KOH, T3- 0.1M KOH, T4- 1M KOH and was mixed well. In the third part, a small thin epidermal strip was taken from the three subjects (tomato fruit, pigweed stem and purple heart leaves) and was examined under the microscope.

IV. Results

Part 1. Determination of chemical property

        [pic 1][pic 2]

Fig. 1 Extract from Tomato fruit (Lycopersicom             Fig. 2 Extract from Pigweed stem (Portulaca                                                                                                                                                                        

           esculentu) with petroleum ether                                   oleracea) with petroleum ether

[pic 3]

                                               Fig. 3 Extract from Purple heart leaves ( Setcreasea

                                                         purpurea) with petroleum ether

Part 2. Determination of the Effect of pH on Pigment Color

[pic 4][pic 5]

     Fig. 4) Before                                                                      Fig. 5) After

Table 1. Tomato (Lycopersicom esculentu)

Table 2. Pigweed(Portulaca oleracea)

Table 3. Purple heart(Setreacea purpurea)