To determine the missing allele combinations for brown and blonde hair based on the given information, let's break down the genotype of the parents and the possible offspring.
From your description:
- Father's genotype: Bb (Brown hair, where B = brown allele and b = blonde allele)
- Mother's genotype: BB (Brown hair, homozygous for the brown allele)
- Child's genotype: Bb (Brown hair)
In a simple Mendelian model, we can identify the possible allele combinations.
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Crossing the alleles of the father and mother:
- The father (Bb) can pass either B (brown) or b (blonde).
- The mother (BB) can only pass B (brown).
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Possible combinations for the children:
- If the father passes B and the mother passes B: BB (Brown)
- If the father passes b and the mother passes B: Bb (Brown)
From this analysis, the possible offspring combinations between these parents can only yield the following genotypes:
- BB (Brown-haired offspring)
- Bb (Brown-haired offspring)
Thus, in this scenario, the only missing allele combination for the children is bb (which would represent a blonde-haired child). However, with the given parents' combinations (Bb and BB), a bb offspring is not possible.
Therefore, while the only potential alleles for offspring from these parents are BB and Bb, the combination bb (blonde hair) cannot occur in this case due to the mother's homozygous BB genotype.
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