One of the key components in vertebrate limb development is the polarizing region, also known as the zone or polarizing activity of ZPA. Where in the limb bud is this region? What axis of the limb does it help to specify? What properties of this region make it an organizing region Through which signaling molecule does it exert its effects? What is the evidence for the importance of this molecule?

One of the key components in vertebrate limb development is the polarizing region, also known as the zone or polarizing activity of ZPA. Where in the limb bud is this region? What axis of the limb does it help to specify? What properties of this region make it an organizing region Through which signaling molecule does it exert its effects? What is the evidence for the importance of this molecule?

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter9: Cell Communication

Section: Chapter Questions

Problem 13RQ: A scientist observes a mutation in the transmembrane region of EGFR that eliminates its ability to...

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One of the key components in vertebrate limb development is the polarizing region, also known as the zone or polarizing activituy of ZPA. a) Where in the limb bud is this region? b) What axis of the limb does it help to specify? c) What properties of this region make it an organizing region d) Through which signaling molecule does it exert its effects? e) What is the evidence for the importance of this molecule?
The oscillatory clock that drives somite forma-tion in vertebrates involves three essential componentsHer7 (an unstable repressor of its own synthesis), Delta (atransmembrane signaling molecule), and Notch (a trans-membrane receptor for Delta). Notch is bound by Delta onneighboring cells, activating the Notch signaling pathway,which then activates Her7 transcription. Normally, thissystem works flawlessly to create sharply defined somites(Figure Q21–2A). In the absence of Delta, however, onlythe first five somites form normally, and the rest are poorlydefined (Figure Q21–2B). If a pulse of Delta is suppliedlater, somite formation returns to normal in the regionswhere Delta was present (Figure Q21–2C). A diagram ofthe connections between the components of the clockand how they interact in adjacent cells is shown in FigureQ21–2D. In the absence of Delta, why do the cells becomeunsynchronized? What is it about the presence of Deltathat keeps adjacent cells oscillating in synchrony?
The binding of small amounts of hormones to target cell receptors triggers an intricate signal cascade. Why is the signal cascade necessary? Why not just have a simple molecularmechanism between the hormone and cellular effect?
Concept test: Please discuss thoroughly. One of the key components in vertebrate limb development is the polarizing region, also known as the zone or polarizing activity of ZPA. Where in the limb bud is this region? What axis of the limb does it help to specify? What properties of this region make it an organizing region Through which signaling molecule does it exert its effects? What is the evidence for the importance of this molecule?
Coat color in mammals is controlled by a hormone receptor called the melanocortin receptor. When this receptor is bound by the hormone MSH, pigment cells produce dark eumelanin. When the receptor is bound by an MSH antagonist that prevents MSH binding, pigment cells make yellow/red pheomelanin. In the Irish Setter, the overall red coat color could be due to a mutation in the a. receptor that prevents the antagonist from binding. b. receptor that prevents MSH from binding. c. MSH protein such that it binds the receptor more efficiently. d. antagonist such that it no longer binds to the receptor.
In response to a hormone secreted by a cell of the opposite mating type, a yeast cell undergoes a complex series of physiological changes involving the activity of about 200 genes and cytoplasmic proteins. They include blockingDNA synthesis, growing toward the mating partner, fusion of the plasma membranes of the two cells, and fusion of their nuclear membranes. Explain how all these events can be controlled through a complex signaling cascade that is triggered by the binding of the hormone to a G protein–linkedreceptor.
Steroid hormones are required by the body at puberty and into adolescence to regulate growth and cell division at more rapid pace than in later life. This regulation occurs via their interaction with cellular receptors and the signaling cascades/pathways that follow. Describe for me the difference between the two major classes of steroids, anabolic and catabolic steroids. What might you expect the result of signaling cascades to be in cells receiving either anabolic or catabolic “signals”? (B) At some point in late adolescence, steroid production decreases by almost 100 fold, as we transition into “adulthood”. Why might we wish to stop these signals from constantly being in our blood stream, (like, Say, between 17-24 years of age)? What result might these steroids have on cancer cells where abhorrent signaling is already causing an increased rate of cell division/growth? Could steroid use result in Cancer?
A scientist observes a mutation in the transmembrane region of EGFR that eliminates its ability to be stabilized by binding interactions during dimerization after ligand binding. Which hypothesis regarding the effect of this mutation on EGF signaling is most likely to be correct? EGF signaling cascades would be active for longer in the cell. EGF signaling cascades would be active for a shorter period of time in the cell. EGF signaling cascades would not occur. EGF signaling would be unaffected.
Thyroid hormone receptor (TR) regulates growth, development, and differentiation of mammals. TR contains both a domain that binds to T3, the thyroid hormone, and a separate domain that binds to DNA. Which of the following BEST explains how TR signals? A. T3 binds to TR at the cell membrane, which then releases second messengers to regulate gene expression. B. T3 binds to DNA at the cell membrane, which then releases second messengers to regulate gene expression. C. T3 diffuses through the cell membrane to bind to TR, which then binds to DNA to regulate gene expression. D. T3 diffuses through the cell membrane to bind to DNA, which then binds to TR to regulate gene expression.
What role, if any, do the noncanonical Wnt signaling pathways have inplanarian regeneration?
A scientist observes a mutation in the transmembrane region of EGFR that eliminates its ability to be stabilized by binding interactions during dimerization after ligand binding. Which hypothesis regarding the effect of this mutation on EGF signaling is most likely to be correct? a. EGF signaling cascades would be active for longer in the cell. b. EGF signaling cascades would be active for a shorter period of time in the cell. c. EGF signaling cascades would not occur. d. EGF signaling would be unaffected.
Which of the following steps amplify the epinephrine signal response in cells: receptor activation of G protein, G protein activation of adenylyl cyclase, cAMP activation of PKA, or PKA phosphorylation of glycogen phosphorylase kinase (GPK)? Which change will have a greater effect on signal amplification: an increase in the number of epinephrine receptors or an increase in the number of Gαs proteins?