Exam 20: Developmental Genetics

Certain mutations in non-Hox genes actually produce homeotic mutants due to a failure to modulate chromatin acetylation appropriately. This influence on cellular "memory" is called what?

A mutation in a fly causes an antenna to develop where a leg should be. This is an example of a ________ mutation.

Mouse eye genes can be inserted into Drosophila and can regulate the flies' eye formation. Differences in size and shape of a zebra are controlled by a gene also found in zebrafish. What do these examples illustrate?

The abdominal segments of Drosophila have no appendages. Loss of function of bithorax genes results in appendages forming in these abdominal segments. Therefore, __________.

Suppose that a homeotic gene from Drosophila is introduced into an Arabidopsis embryo that has a pre-existing mutation in one of its homeotic flower genes. What effect would you expect and why?

Mutations of regulatory elements of developmental genes may have either dominant or recessive effects. If a mutation results in a silencer element that negatively regulates, which do you expect?

Polycomb group (PcG)mutants cause gain-of-function of Antennapedia (Antp)and other homeotic genes by causing some of these genes to be expressed in tissues where they are usually repressed. PcG has a domain that binds to methylated histone H3. This finding supports which of the following hypotheses?

In Drosophila, germ cells develop from pole nuclei isolated from the rest of the embryo at the posterior end. How are they "protected" from the effects of posterior concentrations of zygote-produced mRNAs and proteins?

In the development of C. elegans, an embryo of 1090 cells then loses 131 cells. This is an example of what process?

Flower homoeotic genes encode: __________.

How and when does the Antennapedia complex change antennae into legs?

Use a description of C. elegans development to distinguish clearly between differentiation and determination.

An Antennapedia (Antp)mutant in Drosophila has legs in place of antennae. This is caused by __________.

What characteristic of a cellular blastoderm in Drosophila embryogenesis distinguishes it from the syncytial blastoderm?

In an organism such as a sea urchin, administration of actinomycin D prevents RNA synthesis. However, early development up to gastrula formation can take place in the presence of actinomycin D but gastrulation cannot. This implies that __________.

Use of double mutants has been invaluable in studying developmental pathways. In C. elegans, sex is determined by the ratio of sets of autosomes to X chromosomes. A diploid male has one X, and diploid hermaphrodites have two X's. The loss-of-function gene her-1 produces XO worms that are hermaphrodites, but XX worms are unaffected. Mutation of a second gene, tra, causes the XX to develop as male. Given this information, what would be the phenotype of a tra, her-1 double mutant?

A highly conserved protein domain of 60 amino acids is found in a large number of animals. This domain allows the proteins in question to bind to what?

A pair-rule gene in Drosophila called runt controls some of sex and nervous system formation. In the mouse, runt controls blood cell formation, osteogenesis, and genital structures. In humans, the analog of runt, when mutated, causes children to lack collar bones, and the opening at the top of the skull fails to close. What kind of experiment could tell you whether these genes are conserved in function?

There is much controversy in the news-both scientific and popular-about the use of embryonic stem cells for research. These cells are grown as cell lines in culture, created by taking the inner cell mass from 5-day-old embryos. What is the center of the controversy?

Certain species of lilies, if eaten by pregnant ewes, can cause the ewes to produce lambs with severe birth defects because the plants' cyclopamine can block embryonic response to Shh. This type of birth defect is a phenocopy of mutations in which genes?