Question 3 of 13 10.0 Points Problems Fruit flies homozygous for the recessive m
ID: 278343 • Letter: Q
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Question 3 of 13 10.0 Points Problems Fruit flies homozygous for the recessive mutation scarlet have bright red eyes because they cannot synthesize brown pigment. Fruit flies homozygous for the recessive mutation brown have brownish-purple eyes because they cannot synthesize red pigment. Fruit flies homozygous for both of these mutations have white eyes because they cannot synthesize either type of pigment. The brown and scarlet mutations assort independently. If fruit flies that are heterozygous for both of these mutations are crossed, what kinds of progeny will they produce, and in what proportions? Be very clear and specific...brief answers will receive little to no credit. You must show and explain all work to receive credit. Click on "Show Rich Text Editor" and use the Table button/tool if needed. Maximum number of characters (including HTML tags added by text editor): 32,000Explanation / Answer
Consider the dominant allele for gene for the brown mutation be B, while for scarlet mutation be S. Heterozygous flies for both mutations are BbsSs.
Homozygous for scarlet mutation: BBss (bright red)
Homozygous for brown mutation: bbSS (brownish purple)
Homozygous for both scarlet and brown mutation, giving white flies: bbss
Punnett square for cross between two heterozygous flies is:
Parent 1
BbSs
BS
Bs
bS
bs
Parenr 2
BbSs
BS
BBSS
Dark Red
BBSs
Dark
Red
BbSS
Dark Red
BbSs
Dark
red
Bs
BBSs
Dark Red
BBss
Bright red
BbSs
Dark Red
Bbss
Bright red
bS
BbSS
Dark Red
BbSs
Dark Red
bbSS
Brownish purple
bbSs
Brownish purple
bs
BbSs
Dark red
Bbss
Bright red
bbSs
Brownish purple
bbss
white
Hence, the phenotypes are 9/16 dark red, 3/16 bright red, 3/16 brownish purple and 1 /16 white.
Proportion is 9:3:3:1
Parent 1
BbSs
BS
Bs
bS
bs
Parenr 2
BbSs
BS
BBSS
Dark Red
BBSs
Dark
Red
BbSS
Dark Red
BbSs
Dark
red
Bs
BBSs
Dark Red
BBss
Bright red
BbSs
Dark Red
Bbss
Bright red
bS
BbSS
Dark Red
BbSs
Dark Red
bbSS
Brownish purple
bbSs
Brownish purple
bs
BbSs
Dark red
Bbss
Bright red
bbSs
Brownish purple
bbss
white
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