Question

In guinea pigs, dark hair (D) is dominant over light hair (d) and curly hair (C) is dominant over smooth hair (c). Complete a dihybrid cross for parents with the genotypes: DdCc × DdCc and answer the following in complete sentences.

Describe how you would set up a Punnett square for this cross.
List the likelihood of each possible offspring genotype.
List the likelihood of each possible offspring phenotype.

Answer 1

You begin by making a Punnet Square. :)
Do you remember how to set up a punnet square from class?
You'll get this data:

DDCC - Dark Curly
DDCc - Dark Curly
DdCC - Dark Curly
DdCc - Dark Curly
DDcc - Dark Smooth
Ddcc - Dark Smooth
ddCC - Light Curly
ddCc - Light Curly
ddcc - Light Smooth

Now that you've done this, you'll need to find the likelyhood of each choice.
You have four dark curly, 2 dark smooth, 2 light curly, and 1 light smooth. It should be easy math. :) And so I'm not doing this entirely for you, I think you should go ahead and do it on your own.

Add the fractions of the same physical features together for the phenotypes. :)

Make sense?

Answer 2

Ah, I forgot to explain. Each feature is worth 1/16 because there are 16 features. That's where I got the fractions. :)

Answer 3

Oh I see! I missed this part of the lesson so its been ridiculously hard to catch up with it. Thanks !

Answer 4

No problem. :) I did the same thing back when we did this and had to learn it by myself, too. ;)

Answer 5

for the genotype, would it be 25% dark curly, 12.5% for dark straight and light curly, and 6% for light smooth?

Also, for the phenotype, would I just figure that with all the dark traights over 16, light traits over 16, curly over 16, and straight over 16?