Question

dihybrid crosses advanced mendelian genetics part ii. your turn! problem 1. cross two parent pea plants that are heterozygous for pea color and flower color. use the key on the first page of this handout. 1. first, what are the genotypes for each parent? yy pp 2. what are the phenotypes for each parent? - yellow peas and purple flowers 3. what are the possible allele combinations that each parent may pass down to offspring? yp, yp, yp, yp 4. fill out the punnett square below and perform the analysis as done in the sample problem. f1 genotypes: f1 phenotypes:

Explanation:

Step1: Identify genotypes

Since parents are heterozygous for both traits, genotypes are YyPp for each parent.

Step2: Determine phenotypes

Yellow pea color (Y is dominant over y) and purple flower color (P is dominant over p), so phenotypes are yellow peas and purple flowers for each parent.

Step3: Find allele combinations

Using the principle of independent assortment, possible allele - combinations are YP, Yp, yP, yp for each parent.

Step4: Fill Punnett square

	YP	Yp	yP	yp
Yp	YYPp	YYpp	YyPp	Yypp
yP	YyPP	YyPp	yyPP	yyPp
yp	YyPp	Yypp	yyPp	yypp

Step5: List F1 genotypes

YYPP, YYPp, YYpp, YyPP, YyPp, Yypp, yyPP, yyPp, yypp

Step6: List F1 phenotypes

Yellow - purple: 9 (YYPP, YYPp, YyPP, YyPp combinations), Yellow - white: 3 (YYpp, Yypp combinations), Green - purple: 3 (yyPP, yyPp combinations), Green - white: 1 (yypp)

Answer:

F1 Genotypes: YYPP, YYPp, YYpp, YyPP, YyPp, Yypp, yyPP, yyPp, yypp
F1 Phenotypes: Yellow - purple, Yellow - white, Green - purple, Green - white in ratio 9:3:3:1