Bio 207 PAL th
Week of Oct. 15
Sex Chromosomes and Allele Interactions
1) The A gene controls scale colour for dragons. Individuals with two copies of the A1 allele have
blue scales and individuals with two copies of the A2 allele have green scales. However,
individuals heterozygous for the A gene are green and blue spotted. You cross a green-blue
spotted female dragon with a blue scaled male dragon. The progeny of this cross are: 50 blue
female, 50 spotted female, 50 blue male, 50 green male. Explain the reason for these
phenotypic ratios and draw a Punnett square of this cross.
a) The white gene in Drosophila normally produces flies with red eyes. When the white gene is
mutant, flies have white eyes. The white gene is located on the X chromosome. Perform a
reciprocal cross and show what the results will be for this X-linked gene. List both the
phenotypes of the parents and progeny for each cross.
b) What do you notice about the female progeny? The male progeny?
c) What would be the phenotypes of the progeny if the white gene was not X-linked.
3) The Q locus in