Exam 20: Genes and Development

If a mutant strain of C. elegans failed to produce the Notch ligand, which of the following statements would be TRUE?

Suppose a researcher discovers a new mutant strain of mice in which individuals develop two extra eyes-one on each ear. One hypothesis that would explain this result is a gain-of-function mutation in Pax6 (or in a gene acting downstream of Pax6).

In the graph shown here, the dashed line shows the level of mRNA for a certain protein, Prot7, at various positions along the anterior-posterior axis of an insect embryo. The solid lines portray the levels of two regulatory proteins, A and B, that control translation of the Prot7 mRNA. If both A and B stimulate translation of the Prot7 mRNA, then which graph BEST approximates the expected level of Prot7 across the embryo?

What floral organs would develop in Arabidopsis flower whorls 1, 2, 3, and 4 (in that order) in a mutant in which activity A was expressed in all four whorls and C was expressed in none?

Gurdon's nuclear transplantation experiments with clawed toads supports the hypothesis that:

Therapies using stem cells are already used in:

In the ABC model of floral development, flower development in Arabidopsis is regulated by _____ activities controlled by _____ genes.

Review the ABC model for flower development in Arabidopsis shown below. If additional B activity were expressed in all four whorls, what floral organs would develop from each whorl?

Mutations in the plant Arabidopsis were used to detect the influence of multiple genes on its phenotype.

What floral organs would develop in Arabidopsis flower whorls 1, 2, 3, and 4 (in that order) in a mutant in which activity A was expressed in whorl 1 only and C was expressed in whorls 2, 3, and 4?

The goals of regenerative medicine are to:

The inference that homeotic genes in vertebrates and their corresponding genes in invertebrates evolved from counterpart genes in a common ancestor is supported by the observation(s) that the genes in vertebrates and invertebrates:

As cells continue differentiating, they increasingly lose their developmental potential and their fate becomes more restricted.

Which of the following is present at greater levels at the anterior end of a Drosophila embryo than the posterior end?

Which types of cells are MOST likely to support normal development in nuclear transplant experiments?

Cells become differentiated when certain subsets of genes are deleted.

Signal transduction is the process by which:

A constitutively active receptor will do what in the presence of its ligand?

What is the consequence of inactivating the Notch receptor in the type 2 progenitor cell?

Shown here are four ligands (M, H, K, and L) and their corresponding receptors along with three genes (U, V, and W) whose activity the receptor controls through signal transduction. The arrows indicate gene activation, the T-bars indicate gene repression. If either U or V is required to activate W, which ligand (or ligands) result in W being active?