Exam 18: Developmental Genetics

How does determination relate temporally to differentiation?

Genetic involvement in development appears to be achieved, at least in part, by variable gene activity.

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?

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

A gene that specifies the fate of a particular anatomical segment in Drosophila is called a(n) ________.

From a human developmental standpoint, what is the significance of Hox genes?

Mutations that eliminate a contiguous region in the Drosophila embryo's segmentation pattern are called ________.

Give a brief definition of a homeobox.

Determination is the process whereby a cell's eventual developmental fate is set.

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

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.

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?

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

What is the significance of the homeodomain?

Do Hox gene clusters exist in humans? If so, how many are known to exist?

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

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

Which functions earlier in development: maternal-effect genes or zygotic genes?

During development, many genes act in such a way as to decrease the number of alternative developmental pathways that a cell can follow. Usually there are two alternative developmental paths for a cell to follow. What is the term given to genes that act in this fashion?

The bicoid gene of Drosophila generates embryos with two posterior regions. What is the likely aspect of embryonic development that the bicoid gene probably controls?