Gene interactions

TASK 1:

    Purple color of vetch (wild pea) is caused by the presence of dominant alleles of both genes (C-P-). Others combination of genotypes encodes for white color of flowers.
  1. What is the phenotype ratio in F2 generation? Use Punnett square. What type of gene interaction is it?
  2. What color of flower can be expected in offspring resulting from the following crossings: 1) CcPp x CcPP     2) Ccpp x ccPp?

TASK 2:

    In pumpkin, the shape is determined by two genes: A and B. The pumpkin is round if dominant allele of gene A or of gene B is present in the genotype, it is discoid if dominant alleles of both genes are present, and it is elongated in individuals who are recessive homozygotes in both genes.
  1. What is the phenotype ratio in F2 generation (crossing of two dihybrids)? Use combination square. What type of gene interaction is it?
  2. The crossing of the discoid pumpkin with the round pumpkin resulted in 3/8 discoid, 1/2 round and 1/8 elongated offspring. What were the genotypes of parents and of offspring?

TASK 3:

    The color of a feather of a canary is determined by genes A and B. Dominant allele of gene A encodes for red color, dominant allele of gene B for yellow one. Birds with genotypes aabb and A-B- are white.
  1. What is the phenotype ratio in F2 generation? What type of gene interaction is it?
  2. Third gene (C) determines, if the feather is smooth or fuzzed. Birds with dominant allele C are smooth, recessive genotype determines fuzzed feather. Use branching method to find phenotype ratio in offspring resulting from crossing: AaBbCC x AabbCc.

TASK 4:

    In a pumpkin, the orange color is determined by a dominant allele W, white color by dominant allele Y. Plants with genotypes W-Y- and W-yy are orange, wwY- white and wwyy green.
  1. What is the phenotype ratio in F2 generation? Use Punnett square. What type of gene interaction is it?
  2. What will be the color and phenotype ratio of the offspring after crossing of parents with genotypes: WwYy and Wwyy?

TASK 5:

    The color of a feather of a budgerigar (Melopsittacus undulatus) is determined by the interaction of two genes: F and O. Allele F encodes for yellow color (genotype F-oo) and allele O encodes for blue color (genotype ffO-). If both alleles are present, budgerigar is green (genotype F-O-). Recessive homozygote in both genes is white (genotype ffoo).
  1. What is the phenotype ratio in F2 generation (crossing of two dihybrids)? Use combination square. What type of gene interaction is it?
  2. What will be the feather color and phenotype ratios in the offspring after crossing of parents with genotypes: 1) FFOo x ffOo     2) FfOO x Ffoo?
  3. The crossing of yellow and blue budgerigars resulted in 6 yellow and 5 green offspring. What are the genotypes of parents and offspring?
  4. Green female budgerigar had white offspring. What was the genotype of female and offspring?

TASK 6:

    In mice, the presence of dominant allele of gene C is important for production of dark pigment melanin. Dominant allele of gene A causes change of dark pigment into yellow.
  1. What is the phenotype ratio in F2 generation? Use Punnett square. What type of gene interaction is it?
  2. What offspring will result from crossing of black mouse (CCaa) with white mouse (ccAA)?

TASK 7:

    In chicken, dominant allele of gene A determines colored feather, dominant allele of gene I suppresses effect of gene A, but has no effect on the phenotype.
  1. What is the phenotype ratio in F2 generation (crossing of two dihybrids)? Use Punnett square. What type of gene interaction is it?
  2. What feather can be expected in offspring resulting from crossing: AaIi x Aaii?

TASK 8:

    Scaliness in carp (Cyprinus carpio) is determined by genes S and N. Between these genes, there is reciprocal interaction. The following phenotypes can exist: row (S-Nn), scaly (S-nn), smooth (ssNn), bare (ssnn). The presence of two dominant alleles N in the genotype is lethal.
  1. What are the phenotypes in offspring resulting from crossing of two row carps (SsNn x SsNn)?
  2. Use the branching method to find phenotype ratio in offspring resulting from crossing of row and smooth carps.

TASK 9:

In humans, the color of hair is determined by the interaction of six genes. Gene A encodes for pigment formation and is recessive epistatic against other genes (it means that man with genotype aa is albino). Gene B encodes for formation of brown pigment and is dominant epistatic against R gene (it means that man with genotype bb has fair hair). Gene R encodes for formation of red pigment (recessive allele r is inactive). Dominant alleles D, F, V influence intensity of hair color. In all six genes, there is complete dominance between alleles of individual genes.

Use the branching method to find phenotypes of offspring, if their parents had black hair and genotypes: AaBBRrDDFfVv and AaBBRrDDFfVv

TASK 10:

The coat color of some rodents is determined by the interactions of three genes: A, B and C. Dominant allele of gene C causes albinism and is recessive epistatic against genes A and B. Between genes A and B, there is reciprocal interaction. Dominant allele A determines gray color, recessive allele determines black color. Dominant allele B determines yellow pigmentation of hair ends ("wild color"); recessive allele b has no effect on the phenotype.

Use the branching method to find phenotypes of offspring, if their parents had genotypes: AabbCc x AaBbcc.