GS Activity: Color Challenge (Teacher Version)

Name: ____________________________ Date: ________________

Color Challenge Activity: Thinking about dragon color off-line

GenScope Materials: The Dragon Genome reference sheet

Now that you've worked through some tough color problems in GenScope, here is a set of tough questions about dragon color. Answer these questions off the computer, using only what you have learned so far and the Dragon Genome reference sheet, which describes the dragon genes and color possibilities.

1. Is it possible for a gold dragon to have an azure baby?

Yes or No?

Yes.

By looking at the Dragon Genome sheet, the student will see that a gold dragon is a-/B- and azure is aa/Bb, so yes, she could have an azure baby.

If so, list all the possible colors that the father could be:

Bronze or azure

A bronze male could be Aa/Bb and an azure male would be aa/Bb. Both of these males would provide the necessary a and b alleles needed to match up with the female's a-/B- to produce the azure baby.

Explain your answer.

The explanation should be just like the one given in italics directly above.

2. A gold firebreathing dragon and a Topaz non-firebreathing dragon want to have a baby girl that breathes fire. a. Is it possible for them to have one? Answer yes or no then explain your answer.

Yes. The topaz male, even though he is a non-fire breather, could be heterozygous for firebreathing (Ff), thus making it possible for them to have a fire- breathing daughter.

b. What genes are needed to produce a baby dragon like this?

A female firebreather would have f- on her X chromosomes, and of course, would also have the y chromosome. 3. Is it possible for an emerald dragon to have an azure baby? No. Two a's are needed to produce azure. The emerald mom can only provide a dominant A to her offspring. If so, what are the possible colors the father dragon could be? Not possible Explain. Again, since azure requires two recessive a's and the emerald dragon only has the dominant A, she cannot have an azure son. 4. A gold dragon mates with a bronze dragon. The bronze dragon's chromosomes look like this: Aa/Bb.

These two dragons mate and produce a bunch of baby dragons (offspring). List all of the possible colors for the babies below. Include an explanation using the color genes involved.

Emerald females and topaz and azure males. Emerald is A-/B-. If a-/b- females are produced they die, due to the lethal b allele. The males will be topaz Aa/BB and azure aa/Bb. The a-/B- allele pair comes from the mother and the father contributes A_/B_ or a_/b_.
If crossover were to occur, in addition to the combinations given above, small numbers of gold (a-/B-) females, bronze (Aa/bB) and amethyst (aa/BB) individuals would be produced. The kids will probably not be aware of this possibility. This is for your edification.

5. A gold dragon (which doesn't breathe fire) mates with a bronze dragon (which also doesn't breathe fire). Can they have an amethyst baby which breathes fire? No.

Explain.

Since two recessive f's are needed for a male to breathe fire and the mother doesn't have one (she has the dominant F), none of the sons will be able to breathe fire. However, fire breathing is sex linked. Some daughters could be firebreathing if the father is heterozygous for fire breathing (Ff). He could then contribute the recessive f to his daughter.

6. Would it be possible for them to produce a bronze dragon which does not breathe fire? Yes. Even if Dad does breathe fire, they can produce a non-firebreather because Mom carries the F allele. What genes do you need to produce a bronze dragon?

Aa/Bb are the alleles needed to produce a bronze dragon. Mom contributes an A-/B- and Dad has aa/Bb. Therefore, he can contribute the necessary a and b.

Why are there different sets of colors for male and female dragons?

The color genes are found on the X chromosome, one of the sex chromosomes. Females have only one X chromosome and males have two. Therefore, females have only one set of color alleles, which can be expressed in two ways -- a-/B- or A-/B-. That's because a-/b- and A-/b- are lethal -- the little b does them in. Males have two X chromosomes. Therefore they have two sets of color alleles that can be expressed in many more ways. So they can have any combination of A, a, B, b, except AA/bb or aa/bb. Once again the lethal allele, this time the double lethal, does them in.
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