Exam 20: Developmental Genetics

Immediately after fertilization of a Drosophila egg, the zygote nucleus undergoes a series of divisions. Subsequent nuclear migration generates a(n) _.

In Drosophila, maternal -effect genes are influential in determining the anterior -posterior organization of the developing embryo.

In Drosophila, what is the order of function of the segmentation genes? 18)

Mutations in the selector genes sometimes form structures in the wrong segment, transforming the antenna of a fly into a leg, for example. What are such mutations called?

Which general genetic process is believed to account for the variety of cellular structures and functions in eukaryotic cells?

What is the general order of genes involved in determining early Drosophila development?

How does determination relate temporally to differentiation?

Experiments involving nuclear transplantation in amphibians indicate that nuclei derived from blastula are more likely to support development of complete and normal adults compared with those derived from later stages of development. What do these experiments tell us about the process of development?

Maternal effects are cases of extrachromosomal inheritance in which the genotype of the mother influences the phenotype of her immediate offspring in a non -Mendelian manner. Provide a rationale for the molecular basis of a maternal effect.

What kinds of general observations cause one to conclude that development is the result of variable gene activity?

Which term refers to the regulatory events that establish an initial specific pattern of gene activity and developmental fate for a given cell?

It is often said that development is a two -step process. Which two steps are likely to be referred to here?

Distinguish between segmentation genes and homeotic genes. 20)

Design an experiment that would allow you to determine if a particular nucleus in a Drosophila embryo is capable of directing development of an entire new fly.

Provide a brief description of segment polarity genes, including their regulation and their molecular and developmental effects.

In Drosophila, the sequential order of the function of segmentation genes is _.