A chart shows allele combinations for brown/blonde hair Father's Mother, Bb; Mother's Mother, BB, Mother, Bb; Child, bb. What allele combinations are missing?

Answer 1

Based on the information you provided, we can identify the following allele combinations:

1. Father's Mother: Bb (heterozygous for brown hair)
2. Mother's Mother: BB (homozygous for brown hair)
3. Mother: Bb (heterozygous for brown hair)
4. Child: bb (homozygous for blonde hair)

To determine the missing allele combinations, let's break down the inheritance of the hair color trait.

1. Father's Genotype: We don't have direct information about the father's genotype. His genotype could be either BB (homozygous for brown hair) or Bb (heterozygous), since the Mother, being Bb, could pass on either allele.

2. Possible Offspring Combinations:

   • If the father is BB:
     • Possible combinations with Mother Bb: 50% BB (brown) and 50% Bb (brown). No possibility of bb (blonde) child, which contradicts with the child's genotype (bb).
   • If the father is Bb:
     • Possible combinations with Mother Bb: 25% BB (brown), 50% Bb (brown), 25% bb (blonde).

Since the child is bb, the father must be Bb.

Summary of relevant alleles:

• The father (Bb) is missing from the chart.
• The child's genotype is completely represented as bb.

In summary:

The missing allele combination is that of the father, which is Bb (heterozygous for brown hair). There are no other combinations missing, as the other persons listed (Mother's Mother and Mother) are fully represented.