6. Unlike tetrapods or many other reptiles, snakes have no limbs. Analysis of expression of their homeotic genes shows that for three types of homeotic genes, which for convenience we will call HoxY (yellow), HoxB (blue), and HoxR (red) in the figure, the pattern of expression is different in embryos of snakes than it is in reptilian tetrapod embryos, including chick embryos. The arrows in the figure indicate the regions in the embryo from which certain adult structures arise. Anterior Anterior Forelimb Thoracic Thoracic vertabrae vertabrae НоxR Нохв Posterior HoxY Posterior Chick embryo Python embryo Biology: How Life Works, Second Edition O 2016 W.H. Freeman and Company Which of the following would be required to produce a forelimb in snakes? Briefly explain your answer. A. the combination of yellow and blue expressed together B. the combination of yellow and red expressed together C. the combination of blue and red expressed together D. the combination of yellow, blue, and red expressed together

6. Unlike tetrapods or many other reptiles, snakes have no limbs. Analysis of expression of their homeotic genes shows that for three types of homeotic genes, which for convenience we will call HoxY (yellow), HoxB (blue), and HoxR (red) in the figure, the pattern of expression is different in embryos of snakes than it is in reptilian tetrapod embryos, including chick embryos. The arrows in the figure indicate the regions in the embryo from which certain adult structures arise. Anterior Anterior Forelimb Thoracic Thoracic vertabrae vertabrae НоxR Нохв Posterior HoxY Posterior Chick embryo Python embryo Biology: How Life Works, Second Edition O 2016 W.H. Freeman and Company Which of the following would be required to produce a forelimb in snakes? Briefly explain your answer. A. the combination of yellow and blue expressed together B. the combination of yellow and red expressed together C. the combination of blue and red expressed together D. the combination of yellow, blue, and red expressed together

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter12: Mendel, Genes, And Inheritance

Section: Chapter Questions

Problem 9TYK: The ability of humans to taste the bitter chemical phenylthiocarbamide (PTC) is a genetic trait....

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1. The easily observed external structures in insects, such as different pairs of legs, antennae, and wings form from imaginal discs. a) How is the identity of the different Drosophila imaginal discs established in the embryo—for example, how is it determined whether a disc will form a wing, a leg, or some other structure? b) Dominant mutants in the gene Antennapedia result in fore legs forming in the location where antennae are expected. How does this mutant phenotype illustrate your response to Part a?
The ability of humans to taste the bitter chemical phenylthiocarbamide (PTC) is a genetic trait. People with at least one copy of the normal, dominant allele of the PTC gene can taste PTC; those who are homozygous for a mutant, recessive allele cannot taste it. Could two parents able to taste PTC have a nontaster child? Could nontaster parents have a child able to taste PTC? A pair of taster parents, both of whom had one parent able to taste PTC and one nontaster parent, are expecting their first child. What is the chance that the child will be able to taste PTC? Unable to taste PTC? Suppose the first child is a nontaster. What is the chance that their second child will also be unable to taste PTC?
2. a. You want to create a genetic construct that will express GFP in Drosophila. In addition to the GFPcoding sequence, what DNA element(s) must youinclude in order to express this protein in flies if theconstruct were integrated into the Drosophila genome? Where should such DNA element(s) be located? How would you ensure that GFP is expressedonly in certain tissues of the fly, such as the wing?b. Suppose you insert the GFP coding region plus allof the DNA elements required by the answer to part(a)—except the enhancer—between inverted repeatsfound at the ends of a particular transposable element.Because all of the DNA sequences located betweenthese inverted repeats can move from place to placein the Drosophila genome, you can generate manydifferent fly strains, each with the construct integrated at a different genomic location. You now examine animals from each strain for GFPfluorescence. Animals from different strains showdifferent patterns: some glow green in the eyes,others in…
1. How do muscle cells remain differentiated as muscle cells? 2. A mutation occurs in the Drosophila doublesex gene that prevents Tra from binding to the dsx RNA transcript. What would be the consequences of this mutation for Dsx protein expression in males? In females?
5. While exploring the human genome, a geneticist happens upon a gene in humans that is not functional and is not currently being expressed. This gene appears to be similar to the genes found in modern monkeys that cause tail formation. The most likely explanation for this gene in humans is Group of answer choices a. The gene is lying in wait for when it will be needed and then activated when the opportunity arises b. The gene is a conserved gene that serves an essential function in modern humans c. Humans are likely evolving a tail, and the gene will be expressed in the future d. The gene Is a random mutation of no significance e. The gene is a pseudogene leftover from when human ancestors had a tail
1. Using the data available Using the data available on Moodle describe the phenotype that you observe when each of these three genes is knocked down using RNAi. Remember to compare the worms on control RNAi plates with worms on each of the RNAi knockdown plates. In each case state how do these phenotypes relate to the function of the gene. describe the phenotype that you observe when each of these three genes is knocked down using RNAi. Remember to compare the worms on control RNAi plates with worms on each of the RNAi knockdown plates. In each case state how do these phenotypes relate to the function of the gene. 2. Describe further experiments that you could do that would confirm your findings.
6. Suppose a particular gene is required for early development and also later for development of a particulartissue, such as the adult nervous system. By generating a homozygous mutant clone in that tissue of a heterozygote, researchers can circumvent the lethalitythat would result if the entire animal is homozygousfor a loss-of-function mutation in that gene.A technique called MARCM (Mosaic Analysiswith a Repressible Cell Marker) was developed to enable Drosophila geneticists to generate homozygousmutant cell clones that are marked by the presence of areporter protein such as GFP. Marker expression enables the investigator to observe clearly the mutantphenotype within a clone of mutant cells. This technique relies on a yeast protein called Gal80 that is anegative regulator of the Gal4 protein described previously in Solved Problem II. Gal80 binds to Gal4 andprevents it from activating transcription. The idea ofMARCM is that Gal4/UASG-driven GFP expression isblocked by Gal80 throughout…
1. In most animals, a larger amount of cytoplasm is carried by the egg than by the sperm. Similarly, the egg in plant carries more cytoplasm than the pollen. How could this difference affect the expression of inherited trait [a] dependent on nuclear genes and [b] dependent on extranuclear genes?
Muscle cells differ from bone cells because ________. a. they carry different genes b. they use different genes c. both a and b
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Discuss Concepts Many human diseases are caused by recessive alleles that are not expressed in heterozygotes. Some people think that eugenicsthe selective breeding of humans to eliminate undesirable genetic traitsprovides a way for us to rid our populations of such harmful alleles. Explain why eugenics cannot eliminate such genetic traits from human populations.
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