To analyze:
The activity of RNA polymerase II is inhibited by Actinomycin D. When actinomycin D is present, early development in many vertebrate species, for example frogs, can begin after the formation of a blastula (hollow ball of cells that forms after early cleavage divisions), but development stops before gastrulation. Question asked to discuss the activity of maternal gene in contrast to activity of zygotic gene in early frog development.
Introduction:
Drosophila is the model organism of study of development. It is a well studied genome sequence. Multiple genes are involved in the development of drosophila. The gene that directs the development and fate of an organism are known as developmental genes. Bicoid and Nanos are maternal effect genes; the egg receives these from the mother. Bicoid and Nanos play an important role in creating the anterior to posterior axis. The genes are activated in the fertilized egg (Zygote). In contrast to maternal effect genes, these genes are transcribed by zygotic DNA.
Want to see the full answer?
Check out a sample textbook solutionChapter 18 Solutions
Pearson eText Genetic Analysis: An Integrated Approach -- Instant Access (Pearson+)
- Nanos is a strict maternal-effect gene in Drosophila; that is not transcribed in the embryo. Mutations in nanos result in the loss of posterior structures in the embryo. Predict the phenotype (i.e. wild type or mutant) of the following embryos.arrow_forwardImagine a scenario in which prenatal testing of a human female fetus indicates that the baby will have a normal XX karyotype but is heterozygous for a mutation that inactivates the Xist promoter. Allele “Xr” represents the mutated version of the Xist promoter, and “XR” represents the normal version of the Xist promoter. How will this mutation affect the process of X inactivation?A. "X inactivation will still be random with both mutant and normal X chromosomes being randomly inactivated" B. "The chromosome with the mutant Xist promoter will always be active" C. "The chromosome with the mutant Xist promoter will always be inactivated" D. "The normal X chromosome (no mutation in Xist) will always be active" E. "The normal X chromosome (no mutation in Xist) will always be inactivated"arrow_forwardSuppose a researcher has three different Drosophila strains that have mutations in the bicoid gene called bicoid-A, bicoid-B, and bicoid-C; the wild type is designated bicoid +. To study these mutations, phenotypically normal female flies that are homozygous for the given bicoid mutation were obtained, and their oocytes were analyzed using a Northern blot to determine the size and/or amount of the bicoid mRNA and in situ hybridization to determine the bicoid mRNA location within the oocyte. A wild-type strain was also analyzed as a control. In both cases, the probe was complementary to the bicoid mRNA and the results are shown below. (Anterior is on the left; posterior is on the right.) Northern blot 1 2 - 3 4 In situ hybridization Wild type Lane 1. Wild type (bicoid*) Lane 2. bicoid-A Lane 3. bicoid-B Lane 4. bicoid-C bicoid-B bicoid-A bicoid-C Which mutation is likely to cause the embryo to develop two "anterior" ends? bicoid-B Obicoid-A bicoid-Carrow_forward
- The oncogenic protein BETA promotes entry into the S phase of the cell cycle. Phosphorylation of BETA at the amino acid Tyr98 causes BETA to be degraded by the proteasome, thus limiting its abundance. A mutation in the codon encoding Tyr98 changes this residue to Cys, which cannot be phosphorylated. What is the best description of this mutant allele?a) antimorphb) hypermorphc) hypomorphd) amorphe) neomorpharrow_forward“In an organism that reproduces asexually, there is no difference between a somatic cell mutation and a germ line mutation.” Is this statement true? Explain.arrow_forwardThe transcription factor Pax6 is required continually during the life of a mouse (or a human) for the development of the retina. Homozygous Pax6 knockout mice die soon after birth because Pax6 protein is also required in essential organs, such as the pancreas. a) In order to study the role of Pax6 in eye development a researcher wants to generate a mouse that expresses Pax6 everywhere except in its eyes. Describe how you could construct such a mouse by floxing the gene. Is it possible to achieve the same end with a transgene? (Hint: think about using cDNA and RNAI) b) Suppose you want to create a mouse similar to that in part (a), but one where the eye cells from Pax6 function has been removed and now express a gene that specifies a green fluorescent protein (GFP). Marking the cells in this way will allow the investigators to see the shapes of the Pax6- eye cells more easily than if they did not express GFP. Diagram a Pax6 gene construct that would enable the researcher to do this…arrow_forward
- What would be the most likely effect of inhibiting the translation of hunchback mRNA throughout a Drosophila embryo?arrow_forwardDescribe the appearance of a Drosophila embryo, in which the knirps gene protein-coding sequence has been replaced by lacZ, following incubation in a solution of X-gal.arrow_forwardDrosophila females homozygous for loss-of-functionmutations in the gene aubergine are sterile. RNA-Seqexperiments show that in the ovaries of these females,the levels of RNAs for many kinds of transposable elements are more than 10× higher than in wild-type ovaries. The aubergine gene encodes a Piwi-family protein.a. Why do you think these females are sterile?b. Piwi proteins interact with piRNAs that are transcribed from piRNA gene clusters. Given that thelevels of many kinds of TEs are elevated in mutantovaries, what kinds of DNA sequences do youthink are located in these clusters?c. Many investigators think of piRNAs as a kind ofdefensive mechanism that protects organisms fromthe effects of new transposable elements that mightbe introduced into genomes, for example fromother species. Explainarrow_forward
- You found a strain of mutant fruit flies (Drosophila) living on the rotten bananas in your dorm room. You notice that many of the larvae have abnormal abdominal segments. You want to know if the “abdomenless” mutation is a maternal effect gene. Describe an experiment you would do to determine this, and the results that would support and contradict the notion that the abdomenless gene encodes a maternal determinant.arrow_forwardA C. elegans (nematode) gene called par-1 helps todetermine the AP axis of the animal early in development. Scientists determined that par-1 is pleiotropic—it also has a later function in forming the vulva of theadult animal. How could researchers circumvent thelethality of par-1− mutants to observe the later function of the par-1 gene? (Hint: C. elegans larvae caneat bacteria expressing RNAi for any gene.)arrow_forwardThe Drosophila gene Sex lethal (Sxl) is deserving of itsname. Certain alleles have no effect on XY animals butcause XX animals to die early in development. Other alleles have no effect on XX animals but cause XY animals to die early in development. Thus, some Sxl allelesare lethal to females, while others are lethal to males.a. Would you expect a null mutation in Sxl to causelethality in males or in females? b. Why do Sxl alleles of either type cause lethality ina specific sex?The gene transformer (tra) gets its name from sexualtransformation, as some tra alleles can change XXanimals into morphological males, while other traalleles can change XY animals into morphologicalfemales.c. Which of these sex transformations would becaused by null alleles of tra and which would becaused by constitutively active alleles of tra?d. In contrast with Sxl, null tra mutations do notcause lethality either in XX or in XY animals.However, the Sxl protein regulates the productionof the Tra protein. Why…arrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education