Drosophila mutations such as bcd,if homozygous in the mother,produce offspring with lethal defects,no matter what the genotype of the offspring.For some other genes,the mutant phenotype can be "rescued" by introducing a wild-type allele.Why the difference?
A)Non-rescuable mutations are of paternal origin.
B)Rescuable mutations act as dominants.
C)bcd is a maternal effect mutation.
D)Rescue requires recombination between the maternal and introduced alleles.
E)bcd is a Hox gene.

Question

Quizplus · Accepted Answer

The fact that the mutant phenotype is only observed when the mutation is homozygous in the mother indicates that the mutation is a maternal effect mutation. This means that the genotype of the mother determines the phenotype of the offspring. In the case of bcd, the mutant phenotype cannot be rescued by introducing a wild-type allele because the mutation affects early developmental processes that are dependent on the maternal mRNA and protein deposits in the egg. On the other hand, mutations in other genes may be rescued by introducing a wild-type allele because the gene product is required later in development and can be supplied by the introduced allele.

Drosophila Mutations Such as Bcd,if Homozygous in the Mother,produce Offspring