In the rat, coat color is affected by a gene on chromosome 5 which has two allel
ID: 205329 • Letter: I
Question
In the rat, coat color is affected by a gene on chromosome 5 which has two alleles, B for black and b for brown. Black is dominant to brown. Another gene on chromosome 14 affects the pattern of coat color. This gene has two alleles. P^H is the allele for hooded, in which the animal is mostly white with color restricted to the shoulders and neck. P^+ is the normal solid body color allele. These two alleles exhibit incomplete dominance, so that heterozygotes are mostly colored but have white bellies. Suppose that a true-breeding black hooded strain is crossed with a true breeding brown solid colored strain. The F1 generation rats are then intercrossed to produce an F2 generation. What phenotypes will there be in the F2 generation and in what portions are they expected? Show ALL punnett squares
Explanation / Answer
Answer:
Black=B; Brown = b
Hooded = PHPH
Solid = P+P+
White bellies = PHPh
Black, hooded (BB PHPH) x Brown, solid (bbPhPh) ----P1
Bb PHPh (black, white bellies) -----F1
F1 X F1
BPH
BPh
bPH
bPh
BPH
BBPHPH (Black, hooded)
BBPHPh (Black, white bellies)
BbPHPH (Black, hooded)
BbPHPh (Black, white bellies)
BPh
BBPHPh (Black, white bellies)
BBPhPh (Black, solid)
BbPHPh (Black, white bellies)
BbPhPh (Black, solid)
bPH
BbPHPH (Black, hooded)
BbPHPh (Black, white bellies)
bbPHPH (Brown, hooded)
bbPHPh (Brown, white bellies)
bPh
BbPHPh (Black, white bellies)
BbPhPh (Black, solid)
bbPHPh (Brown, white bellies)
bbPhPh (Brown, solid)
Black, hooded = 3/16
Black, white bellies = 6/16
Black, solid = 3/16
Brown, hooded = 1/16
Brown, white bellies = 2/16
Brown, solid = 1/16
BPH
BPh
bPH
bPh
BPH
BBPHPH (Black, hooded)
BBPHPh (Black, white bellies)
BbPHPH (Black, hooded)
BbPHPh (Black, white bellies)
BPh
BBPHPh (Black, white bellies)
BBPhPh (Black, solid)
BbPHPh (Black, white bellies)
BbPhPh (Black, solid)
bPH
BbPHPH (Black, hooded)
BbPHPh (Black, white bellies)
bbPHPH (Brown, hooded)
bbPHPh (Brown, white bellies)
bPh
BbPHPh (Black, white bellies)
BbPhPh (Black, solid)
bbPHPh (Brown, white bellies)
bbPhPh (Brown, solid)
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