I have white and black pet rats. My female is white and my male is black. I deci
ID: 89538 • Letter: I
Question
I have white and black pet rats. My female is white and my male is black. I decide I want to begin selling pet rats so I breed my rats. The first litter produced all gray haired rats. Darn, I wanted white and black rats like the parents. What could possible explain this? Assign letters to the alleles. What are the parent’s genotypes? What is the genotype of the F1? Would I be able to obtain what I want if I crossed two gray rats? Show me the Punnett square and tell me what my results would be-phenotypically and genotypically.
Explanation / Answer
Parents => Female white * Male black
F1 - All grey haired rats
WW (white) * BB (black)
F1- WB WB WB WB – all grey
This is an example of incomplete dominance.
Incomplete dominance is an intermediate inheritance where any of the two alleles is not completely expressed in heterozygous condition as it is expressed in homozygous state. As a result, another new phenotype will appear which is considered to be a combination of the two phenotypes of the two alleles.
So, the heterozygous state of white and black will appear as grey here. Here neither white nor black allele is completely dominating the other.
If the F1s are crosses
WB * WB
F2 – WW (white), WB (grey), BW (grey), BB (black)
Yes, crossing F1 hybrids will get you white and black offsprings.
F1
W
W
B
WB (grey)
WB (grey)
B
WB (grey)
WB (grey)
Crossing of F1s
F2
W
B
W
WW (white)
WB (grey)
B
WB (grey)
BB (black)
F1
W
W
B
WB (grey)
WB (grey)
B
WB (grey)
WB (grey)