Figure 2 shows the inheritance of sickle cell anaemia in one family Persons 8 and 9 in Figure 2 are expecting a second child. Determine the probability that the child will be a girl with sickle cell trait. You should: • draw a Punnett square diagram • identify the phenotype of each offspring genotype • use the symbols: HA = normal haemoglobin allele HS = mutated haemoglobin allele. – 7068

One thought on “Figure 2 shows the inheritance of sickle cell anaemia in one family Persons 8 and 9 in Figure 2 are expecting a second child. Determine the probability that the child will be a girl with sickle cell trait. You should: • draw a Punnett square diagram • identify the phenotype of each offspring genotype • use the symbols: HA = normal haemoglobin allele HS = mutated haemoglobin allele. – 7068”

1. Father’s gametes: Hᴬ + Hᴬ
   Mother’s gametes: Hᴬ + Hˢ
   Offspring genotypes: HᴬHᴬ, HᴬHᴬ, HᴬHˢ, HᴬHˢ
   Correct phenotypes for each genotype (e.g., HᴬHᴬ = normal, HᴬHˢ = sickle cell, etc.)
   Probability of getting a child with genotype HˢHˢ = 0.25 or 25% or 1 in 4 or ratio 1:3

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