The Role Of Pigments In Red Wandering Jews

Plant Pigment Lab
Question: What pigments are present in Red Wandering Jews?
Background: A leaf is filled with many pigments. The pigments are usually masked by the prevalence of the green chlorophyll. Anothocyanin(red or purple), carotene(orange), and xanthrophyll(yellow) are found in different proportions in different leaves. Leaf pigments can be separated by using paper chromatography. Paper chromatography is a technique that extracts pigments into a paper filter called chromatogram.
What are the pigments are in Red Wondering Jews?
Carotenoids
These pigments primarily absorb in the blue wavelengths, allowing the longer wavelengths to be scattered and producing the yellow color. In autumn foliage, the carotenoids are left over in the chloroplasts and revealed from the loss of chlorophyll.
Chlorophylls
The chlorophylls, A and B, are the pigments of photosynthesis.
They are produced in chloroplasts in the photosynthetic tissues of the leaf. Chlorophyll is normally broken down towards the end of the leaf life span, and much of the nitrogen is reabsorbed by the plant.
Anthocyanins
These are responsible for the pink-red colors of most flower petals, of most red fruits (like apples) and almost all red leaves during the autumn. Anthocyanins absorb light in the blue-green wavelengths, allowing the red wavelengths to be scattered by the plant tissues to make these organs visible to us as red.
Hypothesis: If we test the Red Wandering Jew leaves for pigments then we will find anthocyanin in the leaves because there is purple in the leaves.
Control Variable:
Solvent
Manipulated Variable: Leaves
Responding Variable: Pigments in Red Wandering Jews
Materials: 3 small test tubes, 15mL of rubbing alcohol, 3 strips of filter paper(chromatogram), scissors, pencil, ruler, 3 leaves of Red Wandering Jews, test tube rack, penny
Procedure:
1. Cut a strip of filter paper so it will fit into the test tube. The strip should be 1 in. taller than the test tube and it should be narrow so its edges will not touch the sides of the test tube. It should be 2 cm in width.
2. Cut one end to a triangular point. It should be an isosceles triangle 1cmx1cmx2cm.
3. Collect 1 leaf of the Red Wandering Jews.
4. With a pencil, make a line 3 cm from the end of the filter paper w/ a point.
5. Use a ruler and imagine a line 0.5 cm above the pencil line.
6. Place the leaf on the imaginary line.
7. Using a penny, press down firmly on the leaf and roll along the imaginary line several times to form a definite purple line.
8. Allow the leaf line to dry.
9. Move leaf down and repeat several times until from the imaginary line to the pencil line is completely covered with the leaf’s pigment.
10. Fill the test tube with 5mL of rubbing alcohol.
11. Place the strip into the test tube.
12. Fold the top edge (1cm) of the filter paper over the test tube. 2cm of the pointy end should be immersed in the solvent.
13. The pigment band should not touch the solvent.
14. After 3 quarters of the filter paper is reached the solvent, remove the filter paper.
15. Mark the highest point reached by the solvent and pigments.
16. Allow the filter paper to dry.
17. Identify the pigments and measure the height of each pigment. Record in data table.
18. Measure the height of the solvent line.
19. Calculate the Rf value for each color. Formula: Distance of pigment/distance of solvent= Rf value.
20. Repeat steps 1-20 for 2 more trials.
Data Table:
Trial 1
Color
Distance Pigment traveled
Distance solvent traveled
Rf value
Observations
Chlorophyll A
6.2 cm
6.2cm
1
Chlorophyll A starts off skinny, but gets wider and wider. Yellow is hard to see. The anthocyanin is barely above the pigment line. Chlorophyll A traveled the same distance as the solvent. Pigment band turned brown.
Anthocyanin
0.5cm
6.2cm
0.08

Yellow
3
6.2cm
0.484

Trial 2
Color
Distance Pigment traveled
Distance solvent traveled
Rf value
Observations
Chlorophyll A
6.8cm
6.8cm
1
All the pigments are really light in color. Anthocyanin is the densest. I can see it clearly. Chlorophyll A is really light; it looks like Chlorophyll B. Chlorophyll A traveled the same distance as the solvent. Pigment band turned brown.
Anthocyanin
1cm
6.8cm
0.147

Trial 3
Color
Distance Pigment traveled
Distance solvent traveled
Rf value
Observations
Chlorophyll A
8cm
8cm
1
Anthocyanin is very visible. Yellow is hard to notice, you can barely see it. Chlorophyll A is the same height as the solvent. It is so light it looks like Chlorophyll B. Pigment band turned brown.
Yellow
6.1cm
8cm
0.7625

Anthocyanin
3.2cm
8cm
0.4

Calculations:
Red in trial 1: 0.5/6.2=0.08. The Rf value is 0.08.
Graph:
Conclusion: In this lab we are trying to find what pigments are present in Red Wandering Jews. I believe Anthocyanin is present in Red Wandering Jews because there is purple in the leaves. I reject this hypothesis because other pigments are also in Red Wandering Jews. For example, chlorophyll a was in the leaves. It had Rf values of 1. Another example, yellow was in the leaves. It had Rf values of 0.484 and 0.7625. There are a lot of errors in my lab. I did not rub the pigment off in same spot into the filter paper. The solvent did not reach 3 quarters of the filter paper. To limit my errors, I need to be careful in squishing the pigment and take out my filter paper at the right time. I believe my results are unreliable because I did not take out my filter paper at the right time. Due to this fact, chlorophyll a keeps traveling the same distance as the solvent. My constraints were time. If I had enough time, then I would take out the filter paper when it is 3 quarters filled. There might be some subjectivity involved due to identifying the pigments. The teacher said she identified the pigments really fast, so she might have not saw a hard to spot pigment or she might of identified the pigments wrong.