Exam 20: Genes and Development

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 both U and V are required to activate W, which ligand (or ligands) result in W being active?

A mutation occurs that causes a defect in the development of skeletal muscle. The mutation would likely have occurred in which of the following kinds of cells in order to produce this defect?

Cellular differentiation progressively restricts cell fate because the unexpressed genes in the cell:

Which of the following graphs illustrates the pattern of Krüppel expression in the Drosophila embryo?

What would you expect to happen if you added activity B to whorl 1 in an Arabidopsis floral meristem?

During morula development, the divisions are more rapid than in most normal adult cells and the individual cells get progressively smaller. Which stage(s) of the cell cycle are probably truncated (made shorter)?

If an anchor cell in a C. elegans embryo failed to produce EGF, then all of the three initial progenitor cells would go on to form type 1 cells, and lateral inhibition will not occur.

The reason scientists hope to develop personalized stem cell therapies is that these therapies would avoid the problem of:

In the graph shown here, the dashed line shows the level of mRNA for a certain protein, Prot6, 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 Prot6 mRNA. If both A and B stimulate translation of the Prot6 mRNA, then which graph BEST approximates the expected level of Prot6 across the embryo?

Biologists often use schematic diagrams to illustrate the regulation of various genes and cell signaling pathways. In these diagrams, an arrow is used to show the activation of one gene by the product of another. The inhibition of the expression of a gene by the product of another is indicated by a horizontal line with a T-shaped end. In the example here, the expression of A blocks the expression of B, while the expression of C promotes the expression of D. $A$ $B$ C\longrightarrowD Choose the model that CORRECTLY shows the regulatory relationships between the nanos, bicoid, caudal, hunchback and Krüppel genes and gene products.

An adult cell that is reprogrammed to be pluripotent is called a(n) _____ stem cell.

In Caenorhabditis elegans vulval development, the fate of the progenitor cells is dependent on their proximity to the _____ cell, which secretes epidermal growth factor.

Which of the following cells, or cell types, has the GREATEST developmental potential?

When the Pax6 transcription factor is transferred from a donor individual of one species into the genome of a recipient individual of a different species, it:

In Drosophila, absence of Bicoid protein results in larvae missing anterior segments and absence of Nanos protein results in larvae missing posterior segments. Suppose you inject Bicoid protein into the posterior region of early embryos lacking Nanos. The expected result would be:

Gehring tested the hypothesis that the Pax6 gene acts as a master regulator of eye development by introducing mouse Pax6 genes into the genome of a Drosophila and activating it in the fly's antennae. What happened, and did it support or refute his hypothesis?

A small group of cells at the growing tip of a plant is called the meristem. As the meristem divides, the resulting cells are able to differentiate into various cell types found in the stems, leaves, and flowers. What type of stem cell is the meristem?

In C. elegans, the anchor cell receives EGF signals from type 1 cells and goes on to form cells lining the interior of the vulva.

An abnormal Drosophila larva that is missing much of its posterior end is likely deficient in _____ function.

Imagine that a scientist introduced a copy of the human Pax6 gene into a mouse. What would likely happen in this scenario?