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 MCC BUNDLE >BI<
- Explain the role of axis formation in development.arrow_forwardWhich of the following best describes the concept of cell differentiation during the development of a multicellular organism? A. During development, all of the genes in the embryo's cells are expressed at first, but fewer and fewer are expressed as time proceeds. B. During development, different sets of genes are deleted from different cell types so that at the end of development, each cell has only the genes it needs. C. During development, different cells become specialized to have different phenotypes even though they all originated from the same cell. ..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
- At which stage of development does the Id protein function? Why is its function important?arrow_forwardFor genes that control pathways of development, loss-of-function mutations are usually recessive whereas gainof-function mutations are usually dominant. Can you suggest a reason why?arrow_forwardHow have we discovered that specific genes control development in an organism like Drosophila?arrow_forward
- 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 embryoarrow_forwardWe know quite a bit about Notch/Delta and Hes gene oscillations during embryonic development. What do oscillations of these genes in the adult neural stem cell niche actually look like? How do these oscillations result in the progression from stem cell to neuron?arrow_forwardA cytoplasmic determinant can control development at the early stages of development because....? Group of answer choices a. it is a universal activator of all genes b. it is present evenly throughout the cytoplasm c. it is activated by cell division d. it is controlled by genes present in the cytoplasm e. it is laid down in the egg cell by the motherarrow_forward
- Gene dosage—the number of copies of a gene that areactively being expressed—is important to proper development. Identify and describe two processes that establish the proper dosage of certain genes.arrow_forwardCarefully distinguish between the terms differentiation and determination. Which phenomenon occurs initially during development?arrow_forwardWhat significance do BRCA1 and BRCA2 have in regard to developing cancer, and what types of cancer are associated with these genes?arrow_forward
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