Ms. Libby Davidson bought three Congo Lily bulbs at a flower show after she was

Question

Ms. Libby Davidson bought three Congo Lily bulbs at a flower show after she was told they were each from different inbred lines. One had red flowers, on yellow flowers, and one white flowers. She determined that flower color was controlled by three alleles at a single gene. Red was found to be codominant with yellow, and both alleles dominant to white. Some of the crosses she made and the resulting progeny are listed below:

Cross Progeny
Red (selfed) All red
Yellow (selfed) All yellow
White (selfed) All white
Red x yellow All orange
Yellow x white All yellow
Red x white All red
Orange (selfed) 1 red: 2 orange: 1 yellow

a. Designate each allele with an appropriate gene symbol.

b. Identify all possible genotypes of the following phenotypes
i. Red
ii. Yellow
iii. White
iv. Orange

c. Determine the expected phenotypes and their ratios in the progeny from each of the following crosses.

i. Orange x white
ii. Orange x red (homozygous)
iii. Orange x yellow (heterozygous)

Explanation / Answer

a.
White = Cw
Red = CR
Yellow = CY

b.
Red = CRCR or CRCw
Yellow = CYCY or CYCw
Orange = CYCR
White = CwCw

c.
i. Orange X white
CYCR X CwCw
Progeny = CYCw (Yellow): CRCw (Red)
Ratio = 1:1

ii. Orange X red
CYCR X CRCR
Progeny = 1 (CYCR = Orange): 1 (CRCR = Red)

iii. Orange X yellow
CYCR X CYCw
Progeny = CYCY (Yellow): CYCw (Yellow): CYCR (orange): CRCw (red)

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