Concept explainers
HOW DO WE KNOW?
In this chapter, we have focused on large-scale as well as the inter- and intracellular events that take place during embryogenesis and the formation of adult structures. In particular, we discussed how the adult body plan is laid down by a cascade of gene expression, and the role of cell-cell communication in development. Based on your knowledge of these topics, answer several fundamental questions:
(a) How do we know how many genes control development in an organism like Drosophila?
(b) What experimental evidence demonstrates that molecular gradients in the egg control development?
(c) How did we discover that selector genes specify which adult structures will be formed by body segments?
(d) How did we learn about the levels of gene regulation involved in vulval development in C. elegans?
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Essentials of Genetics (9th Edition) - Standalone book
- Discuss the role of homeotic genes in development. Explain what happens to the phenotype of a fruit fly when a gain-of-function mutation in a homeotic gene causes the protein to be expressed in an abnormal region of the embryo. What are the consequences of a loss-of-function mutation in such a gene?arrow_forwardZygote Embryo Muscle cells Intestinal cells Liver cells Blood cells Nerve cell Cardiac cells (1) Specialization occurs, resulting in the formation of a great variety of cell types. (2) Genes are inserted into the zygote to allow for the formation of different cell types. (3) The expression of genes responsible for the different cell types is controlled by the placenta. (4) The genetic information in the zygote is divided to produce a complete set for each cell typearrow_forwardI am confused about how stem cell transplants works. If you put a semi differentiated tadpole nucleus in a denucleated egg cell, it’ll develop into a fully formed tadpole, but if you put a fully differentiated tadpole nucleus, it won’t (because the genes have already been expressed in a way where the cytoplasmic determinants cannot operate to the fullest). Then how come in stem cell transplants, you use adult nucleuses that are already developed and transplant them into the denucleated egg cells?arrow_forward
- Which of the following illustrates the regulative nature of early mouse development? (a) the mouse embryo is freeliving prior to implantation in the uterus (b) it is possible to produce a transgenic mouse (c) it is possible to produce a mouse in which a specific gene has been knocked out(d) genes related to Drosophila homeotic genes have been identified in mice (e) a chimeric mouse can be produced by fusing two mouse embryosarrow_forwardThis is one given problem on my homework assignment for developmental biology. Thank you for the help!Describe the effects of FGF and RA on each other in limb bud development. Give a specific example of their effects on each other in this capacity. Knowing this, propose a question/hypothesis to investigate the mechanism of how a specific morphogen controls pattern if you know that the morphogen is both necessary and sufficient AND is expressed in the correct spatial/temporal frame.arrow_forwardAn embryologist measures the concentrations of three morphogens (A, B, C) in a row of cells across an embryo, from anterior to posterior. The morphogens cause the expression of various colored pigments as indicated in the graphs. Anterior Posterior Expression of Blue protein only [A] Expression of Red protein only Expression of Green protein only Anterior Posterior [B] Repression of Purple protein Activation of Red protein Anterior Posterior [C] Activation of Yellow protein Which shows the correct expression of pigments expressed in response to Morphogen A? Anterior Posterior Anterior Posterior Anterior Posterior Anterior Posteriorarrow_forward
- Carefully distinguish between the terms differentiation and determination. Which phenomenon occurs initially during development?arrow_forwardName three possible factors contributing to early asymmetries in a developing embryo (i.e. what are the kinds of things early on that lead to the development of the body axes - dn, a/p, l/r, etc)? In the fruit fly drosophila melanogaster, the anterior-to-posterior body axis becomes segmented into distinct regions. explain the role of the genes bicoid and nanos in this process.arrow_forwardWhat generates the first differences among cells in an early embryo? And what controls the differentiation of all the various cell types as development proceeds?arrow_forward
- Reflect on the understandings of the mechanisms by which cells are able to govern embryonic development. Specifically, what was your current understanding or speculations regarding the molecular mechanisms by which cells are able to: 1. Control their proliferation 2. Transition into different types of cells 3. Move 4. Shape developing tissuesarrow_forwardWhat is organogenesis, and why is this concept important to the process of development?arrow_forwardAnother 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 embryoarrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning