1. Warm up
Something about lactose intolerance?

2. Vocab to know
Pigment = A substance, such as chlorophyll or melanin, that produces a characteristic color in plant or animal tissue.

3. Drosophila fruit fly eye color
Wild Type (+)

4. Drosophila fruit fly eye pigments
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #5
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)
Protein #6
Protein #6 transports all pigments into the eye where they are finally expressed.

5. What if there was no Enzyme #1?
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)
Protein #6
Protein #6 transports all pigments into the eye where they are finally expressed.

6. Brown

7. LAB
Guiding question:
What causes variation in eye color of different Drosophila fruit fly strains?
We will examine flies with four different eye colors:
Red (wild type), Sepia, Scarlet, White

8. LAB Hint: Each type of fly has only one missing enzyme (if any).
Your Task:
Can you determine which fly is missing which enzyme?

9. What is chromatography?
Chromatography is a way to separate the colors into individual pigments.
Different pigments travel with the liquid up the paper at different speeds.

10. Pteridine pigments arranged in order of migration on chromatogram, yellow migrating farthest
Color
Isosepiapterin
yellow
Biopterin
blue
2-amino- 4-hydroxypteridine
Sepiapterin
Xanthopterin
green-blue
Isoxanthopterin
violet-blue
Drosopterins
orange
Top of chromatogram (near solvent front)
Bottom of chromatogram (near sample)
Colors not exact

11. Under normal classroom lightw bw se st +

12. Red eyes (wild type)?

13. Red Eyes. Which enzyme is missing to make red eyes
Red Eyes? Which enzyme is missing to make red eyes? (HINT: this could be a trick question!)
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)
Protein #6
Protein #6 transports all pigments into the eye where they are finally expressed.

14. Sepia Eyes?
Sepia is a shade of brown.
There is no orange in sepia.

15. Sepia Eyes? Which enzyme is missing to make sepia eyes?
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)
Protein #6
Protein #6 transports all pigments into the eye where they are finally expressed.

16. Sepia Eyes? Which pigments will we see in the chromatography?
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)

17. Scarlet Eyes?
Bright shade of red.
No brown

18. Scarlet Eyes? Which enzyme is missing to make scarleteyes?
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)
Protein #6
Protein #6 transports all pigments into the eye where they are finally expressed.

19. Scarlet Eyes? Which pigments will we see in the chromatography?
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)
Protein #6
Protein #6 transports all pigments into the eye where they are finally expressed.

20. White eyes? (white eyes?)
Yes, they can still see.
There is NO pigment in their eyes at all (kind of like albino eyeballs)

21. White Eyes? Which enzyme is missing to make white eyes?
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)
Protein #6
Protein #6 transports all pigments into the eye where they are finally expressed.

22. White Eyes? Which pigments will we see in the chromatography?
Molecule A
(colorless)
Molecule C
(colorless)
Sepiapterin &
Isosepiapterin
(YELLOW)
Enzyme #1
Enzyme #2
Enzyme #3
Molecule B
drosopterin
(ORANGE)
ommochrome pigment
(BROWN)
Enzyme #4
Pigments in eye cells
biopterin
(BLUE)
Protein #6
Protein #6 transports all pigments into the eye where they are finally expressed.

23. Set up your chromatography

24. Recording results RESULTS
In our conditions (type of solvent, type of paper), it’s easiest to see the pigments listed below
It is too difficult to resolve other pigments (overlapping each other, and/or very faint)
The main bands of color you see are the ones listed in the chart below.
Draw a diagram to document what your chromatogram looks like.
Use the data table to summarize data from the chromatogram.
Use (+) for presence of pigment same as in wild type
Use (++) for presence of pigment more than in wild type
Use (–) for absence of pigment
Pigment
Color
Wild type
(+)
White
(w)
Sepia
(se)
Scarlet
(st)
Biopterin
blue
Sepiapterin
yellow
Drosopterins
orange

25. Under normal classroom lightw bw se st +

26. Under UV Lamp w bw se st +

27. Add your data to the class data table
Determine which protein is missing from each of the fruit fly strains

28. Results