Advanced Genetics

[paulh]

I got a PM that I had mixed up queen bee and killer bee in my example (post 6 in this thread). (Thanks, Dennis.) He's right. A queen bee is a lesser pastel spider, while a killer bee is a super pastel spider. So I will try again, with the real queen bee genotype this time. The method is the same though.

Pastave x queenbee is a three gene pair genetics problem.

1. Determine the genes in the father's gene pair(s) and in the mother's gene pair(s).
Pastave gene pairs:
gene pair 1 = mojave mutant gene and normal gene
gene pair 2 = pastel mutant gene and normal gene
gene pair 3 = two normal genes

Queenbee gene pairs:
gene pair 1 = lesser mutant gene and normal gene
gene pair 2 = pastel mutant gene and normal gene
gene pair 3 = spider mutant gene and normal gene

2. Assign a symbol to each gene in the first gene pair. Repeat for each additional gene pair.

M = Mojave mutant gene
M^l = M with lower case L as a super script = Lesser mutant gene
m = normal gene

P = pastel mutant gene
p = normal gene

S = spider mutant gene
s = normal gene

Pastave genotype = M/m P/p s/s
Queenbee genotype = M^l/m P/p S/s

3. Determine the gene in each of the possible sperm and in each of the possible eggs for one gene pair.

4. Draw the Punnett square for that gene pair.

M/m x M^l/m --> 1/4 M/M^l, 1/4 M/m, 1/4 M^l/m, 1/4 m/m
P/p x P/p --> 1/4 P/P, 1/4 P/p, 1/4 p/P, 1/4 p/p
s/s x S/s --> 1/2 s/s, 1/2 S/s

5. If any two or more boxes in the square are identical, add them together.

P/p x P/p --> 1/4 P/P, 1/4 P/p, 1/4 p/P, 1/4 p/p
P/p and p/P genotypes are identical. Therefore,
P/p x P/p --> 1/4 P/P, 2/4 P/p, 1/4 p/p


6. Label each genotype with its phenotype.

M/M^l produces blue-eyed white phenotype
M^l/m produces lesser phenotype
M/m produces mojave phenotype.
m/m produces normal phenotype.

P/P produces super pastel phenotype.
P/p produces pastel phenotype.
p/p produces normal phenotype

S/s produces spider phenotype.
s/s produces normal phenotype.

7. Add identical phenotypes together.

See step 10.

8. Repeat steps 3 through 7 for each additional gene pair.

Done

9. List the genotypes from all the gene pairs, using the genotype tree diagram. Multiply the fractions while going out each branch to get the final fraction.

1/4 M/M^l--1/4 P/P-- 1/2 S/s = 1/32 M/M^l P/P S/s (blue-eyed white, possible spider wobble)
1/4 M/M^l--1/4 P/P-- 1/2 s/s = 1/32 M/M^l P/P s/s (blue-eyed white)
1/4 M/M^l--2/4 P/p-- 1/2 S/s = 2/32 M/M^l P/p S/s (blue-eyed white, possible spider wobble)
1/4 M/M^l--2/4 P/p-- 1/2 s/s = 2/32 M/M^l P/p s/s (blue-eyed white)
1/4 M/M^l--1/4 p/p-- 1/2 S/s = 1/32 M/M^l p/p S/s (blue-eyed white, possible spider wobble)
1/4 M/M^l--1/4 p/p-- 1/2 s/s = 1/32 M/M^l p/p s/s (blue-eyed white)

1/4 M^l/m--1/4 P/P-- 1/2 S/s = 1/32 M^l/m P/P S/s (lesser, super pastel, spider)
1/4 M^l/m--1/4 P/P-- 1/2 s/s = 1/32 M^l/m P/P s/s (lesser, super pastel)
1/4 M^l/m--2/4 P/p-- 1/2 S/s = 2/32 M^l/m P/p S/s (lesser, pastel, spider)
1/4 M^l/m--2/4 P/p-- 1/2 s/s = 2/32 M^l/m P/p s/s (lesser, pastel)
1/4 M^l/m--1/4 p/p-- 1/2 S/s = 1/32 M^l/m p/p S/s (lesser, spider)
1/4 M^l/m--1/4 p/p-- 1/2 s/s = 1/32 M^l/m p/p s/s (lesser)

1/4 M/m--1/4 P/P-- 1/2 S/s = 1/32 M/m P/P S/s (mojave, super pastel, spider)
1/4 M/m--1/4 P/P-- 1/2 s/s = 1/32 M/m P/P s/s (mojave, super pastel)
1/4 M/m--2/4 P/p-- 1/2 S/s = 2/32 M/m P/p S/s (mojave, pastel, spider)
1/4 M/m--2/4 P/p-- 1/2 s/s = 2/32 M/m P/p s/s (mojave, pastel)
1/4 M/m--1/4 p/p-- 1/2 S/s = 1/32 M/m p/p S/s (mojave, spider)
1/4 M/m--1/4 p/p-- 1/2 s/s = 1/32 M/m p/p s/s (mojave)

1/4 m/m--1/4 P/P-- 1/2 S/s = 1/32 m/m P/P S/s (super pastel, spider)
1/4 m/m--1/4 P/P-- 1/2 s/s = 1/32 m/m P/P s/s (super pastel)
1/4 m/m--2/4 P/p-- 1/2 S/s = 2/32 m/m P/p S/s (pastel, spider)
1/4 m/m--2/4 P/p-- 1/2 s/s = 2/32 m/m P/p s/s (pastel)
1/4 m/m--1/4 p/p-- 1/2 S/s = 1/32 m/m p/p S/s (spider)
1/4 m/m--1/4 p/p-- 1/2 s/s = 1/32 m/m p/p s/s (normal phenotype)

10. List the phenotypes from all the gene pairs, using the phenotype tree diagram. Multiply the fractions while going out each branch to get the final fraction.

Done above. The blue-eyed white phenotype masks the effect of the pastel gene (as far as I know). The blue-eyed white phenotype also masks the pattern effect of the spider gene, but not the wobble. Of course, some spiders may not show the wobble immediately. The 8/32 blue-eyed whites can be added together as 8/32 (= 1/4) blue-eyed white, with a 50% probability of also being spider.