The maternal-effect mutation bicoid (bcd) is recessive. In the absence of the bicoid protein product, embryogenesis is not completed. Consider a cross between a female heterozygous for the bicoid mutation and a homozygous male
b.Predict the outcome (normal vs. failed embryogenesis) in the and generations of the cross described.

Verified step by step guidance

1. Identify the genotypes of the parents: the female is heterozygous for the bicoid mutation (bcd/+), and the male is homozygous recessive (bcd/bcd).
2. Understand that bicoid is a maternal-effect gene, meaning the phenotype of the offspring depends on the mother's genotype, not the offspring's own genotype.
3. Determine the possible genotypes of the F1 offspring by performing a Punnett square cross between the female (bcd/+) and the male (bcd/bcd).
4. Predict the phenotype of the F1 generation based on the mother's genotype: since the mother is heterozygous (bcd/+), she produces normal bicoid protein, so all F1 embryos will develop normally regardless of their genotype.
5. For the F2 generation, consider that F1 females may be either bcd/+ or bcd/bcd; only embryos from bcd/bcd mothers will fail embryogenesis due to lack of bicoid protein, so predict the ratio of normal to failed embryogenesis accordingly.

Key Concepts

Maternal-Effect Genes

Maternal-effect genes are genes whose products, usually mRNA or proteins, are deposited by the mother into the egg and influence early embryonic development. The embryo's genotype does not determine the phenotype; instead, the mother's genotype controls the trait. In the bicoid example, the presence or absence of bicoid protein from the mother affects embryogenesis regardless of the embryo's own genotype.

Recessive Mutations and Heterozygosity

A recessive mutation requires two copies of the mutant allele to show a phenotype. A heterozygous individual carries one normal and one mutant allele but typically shows a normal phenotype. In this cross, the heterozygous female produces eggs with either normal or mutant bicoid mRNA, affecting the embryo depending on which allele is inherited maternally.

Genetic Crosses and Generational Outcomes

Predicting outcomes in genetic crosses involves understanding allele segregation and inheritance patterns across generations. Here, crossing a heterozygous female with a homozygous male affects the F1 generation's embryogenesis based on maternal genotype. The F2 generation's phenotype depends on the genotypes of the F1 females, illustrating how maternal-effect mutations influence successive generations.