Autosomal Dominant and Recessive Traits Figure 21.2 shows a few human traits. Wh

Question

Autosomal Dominant and Recessive Traits Figure 21.2 shows a few human traits. What is the r type of hairline? 2. What is the homozygous recessive genotype for finger length? What is the phenotype? 3. Why does the heterozygous individual have freckles? Figure 21.2 Commonly inherited traits in human beings. The alleles indicate which traits are dominant and which are recessive. a. Widow's peak: WW or Ww b. Straight hairine: ww e. Short fingers: S5 or Ss t. Long fingers: ss c. unattached earlobes: EE or Ed. Atached earlobes: ee g Freckles: FF or Ft h. No freckles: ft These genetic problems use the alleles from Figure 21.2 and Table 21.1. 4. Maria and the members of her immediate family have attached earlobes. What is Maria's genotype? Her maternal grandfather has unattached earlobes. Deduce the genotype of her maternal grandfatherExplain. 5. Moses does not have a bent little finger, but his parents do. Deduce the genotype of his parents. of Moses, Explain. Manny is adopted. He has hair on the back of his hand. Could both of his parents have had h back of the hand? 6. air on the Could both of his parents have had no hair on the back of the hand? -Explain. 290 Laboratory 21 Human Genetics 21-2

Explanation / Answer

1.

The dominant homozygous genotype for hair type = WW and the phenotype is widow's peak.

2.

The homozygous recessive genotype of fingers is = ss and phenotype is long fingers.

3.

The heterozygous genotype Ff is characterized by freckles because the 'F' gene dominates the recessive 'f' gene. Hence, freckles hair type is dominant to no freckles.

4.

Maria and her family members have attached earlobes. The genotype of Maria is ee (recessive). Maria maternal grandfather have unattached earlobes and the genotype is EE or Ee (dominant homozygous or heterozygous). The cross between EE and ee may produce offspring with genotype Ee. The cross between Ee and ee may produce offspring with 1/4 Ee and 3/4 ee genotypes.

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