Gryphin eyes can be gold (G), pink (P), or silver (S)

Subject:BiologyPrice:3.86 Bought12

Share With

Gryphin eyes can be gold (G), pink (P), or silver (S). Note: letters in brackets represent the phenotype.

You cross true breeding lines of the different phenotypes to one-another, then intercross the F1s (F1 X F1) and find the following (letters represent phenotypes)

• Cross 1 - Parental: G X S; F1 = S; F2 = 102S: 34G
• Cross 2 - Parental: P X S; F1 = P; F2 = 117P: 39S
• Cross 3 - Parental: P X G; F1 = P; F2 = 96P: 24S: 8G

You are not the only scientist working on gryphin genetics and while you're performing your crosses a paper is published showing that two genes are involved in gryphin eye colour.

We will call these genes A, and B. There are two alleles of each - A and a; B and b.

Using the cross results above what were the parental genotypes and the genotype of the F1 for each cross (Cross 1, Cross 2 and Cross 3), above. Make sure in your answer it's clear how genotype (genes A and B) and phenotype (pink, gold, silver) are related. (6 marks)

Hint: Start with Cross 3. Review how we got a 9:7 phenotypic ratio when two genes complement each other (instead of 9:3:3:1); we calculated 7 by adding multiple categories from the Mendelian 9:3:3:1 ratio together based on how the genes were interacting -> 3 + 3+ 1 = 7. What might a 96:24:8 ratio suggest (95:25:8 = 12:3:1)?