Warm up

• Something about lactose intolerance?

Vocab to know

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

Drosophila fruit fly eye color

Wild Type (+)

Drosophila fruit fly eye pigments

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

Enzyme #5

Protein #6

Protein #6 transports all

pigments into the eye where they are finally expressed.

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

What if there was no Enzyme #1?

Protein #6

Protein #6 transports all

pigments into the eye where they are finally expressed.

Brown

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

LAB

Hint:

Each type of fly has only one missing enzyme (if any).

Your Task:

Can you determine which fly is missing which enzyme?

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.

Pteridine pigments arranged in order of migration on chromatogram, yellow migrating farthest

Pigment Color

Isosepiapterin yellow

Biopterin blue

2-amino-4-hydroxypteridine blue

Sepiapterin yellow

Xanthopterin green-blue

Isoxanthopterin violet-blue

Drosopterins orange Bottom of chromatogram (near sample)

Top of chromatogram (near solvent front)

Colors not exact

w bw se st +

Under normal classroom light

Red eyes (wild type)?

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

Red Eyes?Which enzyme is missing to make red eyes? (HINT:

this could be a trick question!)

Protein #6

Protein #6 transports all

pigments into the eye where they are finally expressed.

Sepia Eyes?

• Sepia is a shade of brown.

• There is no orange in sepia.

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

Sepia Eyes?Which enzyme is missing to make sepia eyes?

Protein #6

Protein #6 transports all

pigments into the eye where they are finally expressed.

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

Sepia Eyes?Which pigments will we see in the chromatography?

Scarlet Eyes?

• Bright shade of red.• No brown

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

Scarlet Eyes?Which enzyme is missing to make scarleteyes?

Protein #6

Protein #6 transports all

pigments into the eye where they are finally expressed.

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

Scarlet Eyes?Which pigments will we see in the chromatography?

Protein #6

Protein #6 transports all

pigments into the eye where they are finally expressed.

White eyes? (white eyes?)

• Yes, they can still see.• There is NO pigment in their

eyes at all (kind of like albino eyeballs)

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

White Eyes?Which enzyme is missing to make white eyes?

Protein #6

Protein #6 transports all

pigments into the eye where they are finally expressed.

biopterin(BLUE)

drosopterin(ORANGE)

Sepiapterin & Isosepiapterin

(YELLOW)

Molecule A(colorless)

ommochrome pigment

(BROWN)

Enzyme #2

Enzyme #3

Enzyme #4

Molecule C(colorless)

Pigments in eye cells

Molecule B

Enzyme #1

White Eyes?Which pigments will we see in the chromatography?

Protein #6

Protein #6 transports all

pigments into the eye where they are finally expressed.

Set up your chromatography

Recording resultsRESULTS

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.

1. Draw a diagram to document what your chromatogram looks like.2. Use the data table to summarize data from the chromatogram.

1. Use (+) for presence of pigment same as in wild type2. Use (++) for presence of pigment more than in wild type3. Use (–) for absence of pigment

Pigment Color Wild type

(+)White

(w)Sepia(se)

Scarlet(st)

Biopterin blue

Sepiapterin yellow

Drosopterins orange

w bw se st +

Under normal classroom light

w bw se st +

Under UV Lamp

• Add your data to the class data table• Determine which protein is missing from

each of the fruit fly strains

Results