Following a mutagenesis experiment to identify novel genes affecting the circadian clock in Drosophila melanogaster you discover several mutants. You start considering two of those mutants that you call c and d. The two homozygous c/c and d/d are arrhythmic (arrhythmic is the definition of their
Comparing the number of flies expected for the Parental and the Recombinant genotypes, what can be concluded about the C and D loci? Select only one answer.
1. |
The Parental are much more than the Recombinant, C & D are linked |
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2. |
The Recombinant are much more than the Parental, C & D are linked |
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3. |
The Recombinant are much more than the Parental, C & D are not linked |
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4. |
The Parental are much more than the Recombinant, C & D are not linked |
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5. |
The Parental are equal to the Recombinant, C & D are not linked |
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6. |
The Parental are equal to the Recombinant, C & D are linked |
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- After graduating from UNC Charlotte with the BS in Biology, you get a job with an agro-chemical company and are assigned to a lab that is exploring the use of a newly synthesized compound that may be a possible insecticide. The compound is thought to control insect populations by disrupting the genes that control embryonic development. Your lab conducts an experiment to investigate the influence of the compound on developmental genes by measuring the levels of the proteins the genes code for. You measure protein levels in two groups of insect eggs: the Treatment Group, which is exposed to the compound, and the Control Group, which is exposed to a compound that is known to have no negative effects on gene activity. Your results are shown below. In all graphs, the Control group exhibits normal levels of proteins and gene expression. (Remeber: P > 0.05 means the observed differences are not significant; P < 0.05 means the differences are significant and biologically meaningful).…arrow_forwardYou conduct an experiment to study the expression of the S protein through the tissues of your favorite plant (Arabidopsis thaliana). The morning of the experiment you inject in the leaves a messenger RNA that codes for the synthesis of a single protein made of two parts that are attached to each other: the functional S protein and a red fluorescent protein tag (RFP). You perform two cross sections of the same root, one section at the start of the experiment (time = Oh; corresponding to the time of injection) and one section in the afternoon (time = 8h). Through fluorescent microscopy you observe a change in the coloration inside the cells of the root's central tissues (as indicated by the arrows): from no coloration (time = Oh) to red (time = 8h). • The cells of the central tissues in the roots do not have nuclei or ribosomes. How can you explain this change of coloration? Please provide a cellular feature that can lead to this. • What is one advantage of using an RFP-tag in an mRNA?…arrow_forwardWhat would be the most likely result of injecting bicoid mRNA into the posterior end of a Drosophila embryo and inhibiting the translation of nanos mRNA?arrow_forward
- In the nematode C. elegans, some worms have blisteredcuticles due to a recessive mutation in one of the bligenes. Someone studying a suppressor mutation thatsuppressed bli-3 mutations wanted to know if it wouldalso suppress mutations in bli-4. They had a strain thatwas homozygous for this recessive suppressor mutation,and its phenotype was wild type.a. How would they determine whether this recessivesuppressor mutation would suppress mutations in bli-4?In other words, what is the genotype of the wormsrequired to answer the question?b. What cross(es) would they do to make these worms?c. What results would they expect in the F2 if(1) it did act as a suppressor of bli-4?(2) it did not act as a suppressor of bli-4?arrow_forwardHere are schematic diagrams of mutant Drosophila larvae. The left side of each pair shows a wild-type larva, with gray boxes showing the sections that are missing in the mutant larva. Which type of gene is defective in each larva: a gap gene, a pair-rule gene, or a segment-polarity gene?arrow_forwardWhat is the signaling pathway that mediates the organizing activity of the A/P organizer in the Drosophila wing disc? Describe two experiments that suggest this pathway functions to organize pattern and promote growth along the anterior/posterior axis of wing imaginal discs.arrow_forward
- As we have learned in this chapter, the Nanos protein inhibits the translation of hunchback mRNA, lowering the concentration of Hunchback protein at the posterior end of a fruit-fly embryo and stimulating the differentiation of posterior characteristics. The results of experiments have demonstrated that the action of Nanos on hunchback mRNA depends on the presence of an 11-base sequence that is located in the 3′ untranslated region (3′ UTR) of hunchback mRNA. This sequence has been termed the Nanos response element (NRE). There are two copies of NRE in the 3′ UTR of hunchback mRNA. If a copy of NRE is added to the 3′ UTR of another mRNA produced by a different gene, that mRNA is repressed by Nanos. The repression is greater if several NREs are added. On the basis of these observations, propose a mechanism for how Nanos inhibits Hunchback translation.arrow_forwardDiscuss how the anterior portion of the anteroposterior axis is established in Drosophila. What aspects of oogenesis are critical in establishing this axis? What do you think would happen if the bicoid mRNA was not trapped at the anterior end but instead diffused freely throughout the oocyte?arrow_forwardIt seems that developmental genetics boils down to a complex network of gene regulation. Try to draw a structure of this network for Drosophila. How many genes do you think are necessary to complete the developmental network for the fruit fly? How many genes do you think are needed for a network to specify one segment? Do you think it is more difficult to identify genes that are involved in the beginning, middle, or end of this network? Suppose you were trying to identify all of the genes needed for development in a chicken. Knowing what you know about Drosophila development, would you first try to identify genes necessary for early development, or would you begin by identifying genes involved in cell differentiation?arrow_forward
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