Mendelian Genetics Lab/Hw

Mendelian Genetics HW (10 pts)

Suppose that flower color is inherited by simple dominance and that red flowers are dominant to white flowers. If a homozygous recessive individual is crossed with a homozygous dominant individual, what is the probability of obtaining a pink offspring? (1pt)

100%

75%

50%

25%

0%

Dragon color and wing size are controlled by two separate gene loci with 2 alleles each. A dragon that is red with large wings (RrWw) mates with another that is silver with small wings (rrww). (4.5 pts total)

Write out the genotypes of the 4 gametes (of each parent) that will be used to determine the resultant offspring from the cross. (1.5 pts)

Rr, rr, Ww, ww

Do a Punnett Square to demonstrate all the possible resultant offsprings’ allele combinations (genotypes) from parents having genotypes RrWw and rrww. (1.5 pts)

What are the resultant genotypic and phenotypic ratios? Be sure you indicate what each part of the ratio refers to, i.e. don’t just say 4:3:2. Say what the numbers refer to. (1.5 pts)

Genotypic Ratio:

R’s: 0:2:2 ( 0 = amount of RR, first 2= amount of Rr, second 2= amount of rr)

W’s: 0:2:2 ( 0 = amount of WW, first 2= amount of Ww, second 2= amount of ww)

Phenotypic Ratio:

3:1

Shell color in snails is controlled by a single gene locus with two alleles. Heterozygous orange-shelled (Ss) snails are mated to homozygous recessive white-shelled (ss) snails. (3 pts)

What is the expected genotypic ratio of the offspring?

0:2:2

Predict the phenotypic ratio expected from back-crossing the orange-shelled offspring to the orange-shelled parent type.

2:2

The Manx allele (M) in house cats causes a short or absent tail, while the recessive allele (m) confers a normal tail. The MM genotype is lethal, and cats that are homozygous dominant die as embryos. If two Manx cats mate, what is the probability that each surviving kitten has a...