Meiosis and Mendelian Genetics, Please Show work, thanks! 2) A species of centip
ID: 37229 • Letter: M
Question
Meiosis and Mendelian Genetics, Please Show work, thanks!
2) A species of centipede has a haploid chromosome number of 2. Leg length is controlled by a single gene with two alleles: the long leg allele (L) is dominant to the short leg allele (1). Body coloration is controlled by a single gene with two alleles: the dark allele (D) is dominant to the light allele (d). Leg length and body coloration are encoded by gene on separated chromosomes. Assume the traits obey Mendel?s law of Independent Assortment. a) A centipede that is homozygous for the recessive allele at both loci mates with a centipede that is homozygous for the dominant allele at both bd. They produce 100 offspring. What fraction of the offspring would you expect to have short legs and light body coloration? Show your calculations and reasoning. b) Two centipedes that are each heterozygous for both leg length and body coloration mate and produce loo offspring. What fraction of the offspring would you expect to have long legs and light body coloration? Show your work using a Punnett Square and provide your answer as a fraction.Explanation / Answer
a) when a centipede homozygous for dominant allele at both loci is crossed with a centipede homozygous for recessive allele at both loci, then the fraction of offspring to have short legs and light body coloration can be calculated by using the phenotypic ratio for the dihybrid cross. The ratio is given as:
9:3:3:1
where,
The phenotypic ratios:
DL 9/16
Dl 3/16
dL 3/16
dl 1/16
So for 100 offsprings the fraction of offsprings expected to have short legs and light body coloration is:
1/16 * 100
= 100/16 = 25/4.
b) The gametes for heterozygous centipedes will be : DL, Dl, dL and dl
The punnett square is given below:
From the punnett square the phenotypic ratios are derived as 9:3:3:1
Fraction of offspring expected to have long legs and light body coloration out of 100 offsprings can be calculated as:
3/16 *100
= 300/ 16 = 75/4.
DL Dl dL dl DL DDLL DDLl DdLL DdLl Dl DDLl DDll DdLl Ddll dL DdLL DdLl ddLL ddLl dl DdLl Ddll ddLl ddll