In flies developing from eggs laid by a nanos−mother, development of the abdomen is inhibited.Flies developing from eggs that have no maternallysupplied hunchback mRNA are normal. Flies developing from eggs laid by a nanos− mother that alsohave no maternally supplied hunchback mRNA arenormal. If too much Hunchback protein accumulatesin the posterior of the egg, abdominal developmentis prevented.a. What do these findings say about the function ofthe Nanos protein and of the hunchback maternallysupplied mRNA?b. What do these findings say about the efficiency ofbiological processes that are subject to evolution?

In flies developing from eggs laid by a nanos−mother, development of the abdomen is inhibited.Flies developing from eggs that have no maternallysupplied hunchback mRNA are normal. Flies developing from eggs laid by a nanos− mother that alsohave no maternally supplied hunchback mRNA arenormal. If too much Hunchback protein accumulatesin the posterior of the egg, abdominal developmentis prevented.a. What do these findings say about the function ofthe Nanos protein and of the hunchback maternallysupplied mRNA?b. What do these findings say about the efficiency ofbiological processes that are subject to evolution?

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter17: Developmental Genetics

Section: Chapter Questions

Problem 12TYU

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In flies, the gap gene kruppel is expressed in a broad band in the middle of the embryo with giant expressed as its anterior border and knirps at its posterior border. How is the expression of kruppel limited to this band in the embryo? Describe the spatial regulation of the kruppel gene.
As shown in Figure 13-26, the Sonic hedgehog gene is expressed in many places in a developing chicken. Is theidentical Sonic hedgehog protein expressed in each tissue? If so, how do the tissues develop into different structures? If not, how are different Sonic hedgehog proteinsproduced?
You isolate a glp-1 mutation of C. elegans and discoverthat the DNA region encoding the spatial control region(SCR) has been deleted. What will the GLP-1 protein expression pattern be in a four-cell embryo in mutant heterozygotes? In mutant homozygotes?
“In the early Drosophila embryo, the establishment of different body regionor tissues along, on the one hand, the anteroposterior axis and, on theother, the dorsoventral axis are initiated by clues provided by the egg’smother; however the nature of those signals and the way in which theyoperate is completely different”. Discuss whether this statement is correct.
What is the difference between a maternal-effect gene and a zygotic gene? Of the following genes that play a role in Drosophila development, which are maternal-effect genes and which are zygotic? Explain your answer. A. nanos B. Antp C. bicoid D. lab
a. The eyeless gene is required for eye formation in Drosophila. It encodes a homeodomain. What would you predict about the biochemical function of the Eyeless protein?b. Where would you predict that the eyeless gene is expressed in development? How would you test your prediction? c. The Small eye and Aniridia genes of mice and humans, respectively, encode proteins with very strong sequence similarity to the fly Eyeless protein, and they are named for their effects on eye development. Devise one test to examine whether the mouse and human genes are functionally equivalent to the fly eyeless gene.
Let’s suppose an X-linked gene in mice exists as two alleles, whichwe will call B and b. X-chromosome inactivation, a process inwhich one X chromosome is turned off, occurs in the somatic cellsof female mammals . Allele B encodes an mRNA that is 900 nucleotides long, whereas allele b contains a small deletion that shortens the mRNA to a length of 825 nucleotides.Draw the expected Northern blot that will be obtained usingmRNA isolated from somatic tissue of the followingmice:Lane 1. mRNA from an XbY male mouseLane 2. mRNA from an XbXb female mouseLane 3. mRNA from an XBXb female mouse.Note: The sample taken from the female mouse is not from aclone of cells. It is from a tissue sample, like the one shown.
You isolate a glp-1 mutation of C. elegans and discover that the DNA region encoding the spatial control region (SCR) has been deleted. What will the GLP-1 protein expression pattern be in a four-cell embryo in mutant heterozygotes? In mutant homozygotes?
In Drosophila, both fushi tarazu (ftz) and engrailed (eng) genes encode homeobox transcription factors and are capable of eliciting the expression of other genes. Both genes work at about the same time during development and in the same region to specify cell fate in body segments. To discover if ftz regulates the expression of engrailed;if engrailed regulates ftz; or if both are regulated by another gene, you perform a mutant analysis. In ftz embryos (ftz/ ftz) engrailed protein is absent; in engrailed embryos (eng/eng) ftz expression is normal. What does this tell you about the regulation of these two genes—does the engrailed gene regulate ftz, or does the ftz gene regulate engrailed?
What would be the most likely effect of inhibiting the translation of hunchback mRNA throughout a Drosophila embryo?
Which of the following statement(s) is/are true with regard to positional information in Drosophila? A. Morphogens are a type of molecule that conveys positional information. B. Morphogenetic gradients are established only in the oocyte, prior to fertilization. C. Cell adhesion molecules also provide a way for a cell to obtain positional information.
Another way to study the role of proteins (e.g., transcription factors) that function in development is to microinject the mRNA that encodes a protein, or the purified protein itself, into an oocyte or embryo, and then determine how this affects the subsequent development of the embryo, larva, and adult. For example, if Bicoid protein is injected into the posterior region of an oocyte, the resulting embryo will develop into a larva that has anterior structures at both ends. Based on your understanding of the function of each developmental gene, what would be the predicted phenotype if the following proteins or mRNAs were injected into normal oocytes? A. Nanos mRNA injected into the anterior end of an oocyte B. Antp protein injected into the posterior end of an embryo C. Toll mRNA injected into the dorsal side of an early embryo