During sexual reproduction an egg produced by the mother and sperm produced by the father join to form a zygote that develops into an embryo. Which of the following statements is false?
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An experimenter cuts two pieces of tissue (tissue A and tissue B) from different regions of a late gastrula stage frog. When he allows these tissues to grow and develop in separate culture dishes, tissue A gives rise to muscle while tissue B gives rise to skin. He then repeats the experiment with the same tissues from a different embryo, but instead of placing them in separate dishes, he places them next to each other in the same dish. Tissue A tissue again gives rise to muscles, but tissue B tissue gives rise to tooth enamel. One can conclude from these results that, at the time tissue B was removed from the embryo, it was _____.
Eukaryotic transcription regulators _____.usually interact with the bases of DNA through hydrogen bondsHow are eukaryotic transcription regulators able to affect transcription when their binding sites are far from the promoter?DNA looping brings their binding site and their promoter together.Histone modifications can activate gene expression by _____.attracting chromatin remodeling complexes that decondense chromatinA steroid hormone will activate different genes in different cell types. This happens because different cells contain different _____.transcription regulators that form functional complexes with the hormone receptorPost-translational modification of which of the following proteins can lead to a change in gene expression that is passed from parent to daughter cells?HistonesEach _____ gene is expressed in every Drosophila segment.segment polarityYou have found a novel fly mutation that alters the normal expression pattern of the pair-rule gene Eve. Instead of being expressed in 7 stripes, Eve is now expressed only in four stripes. What kind of mutation have you most likely found?A mutation in a gap geneHox genes encode _____.transcription regulatorsWhich of the following sets of genes includes genes that encode paracrine signals?Segment-polarity genesWhich of the following events depend on the presence of VegT in newly fertilized frog eggs?Mesoderm and endoderm formationCortical rotation in a newly fertilized frog egg can be blocked injecting an antibody to kinesin. Which of the following events will NOT be inhibited by this antibody?Expression of NodalIf Noggin and Chordin are depleted, the frog embryo will ventralizedbe ventralized (contain only ventral tissues)Which of the following is a TGF-beta signaling protein?BMP4 and NodalWhich epithelial junction complexes are formed by transmembrane proteins that interact with those in neighboring cells to form channels that allow small molecules to pass between cells?Gap junctionsCadherins _____.all of the other answers are correctNeurulation involves _____.the apical constriction of epithelial cells due to the sliding of actin filaments against myosin filamentsMechanical stresses on epithelial cells are transmitted from cell to cell by cytoskeleton filaments anchored to cell-cell adhesion sites. Adherens junctions attach to _____ and desmosomes attach to _____.actin filament, intermediate filamentsAn adult hemopoietic (blood) stem cell found in the bone marrow _____.can undergo self-renewing divisions for the lifetime of a healthy animalInduced pluripotent stem (iPS) cells _____.can be created by the expression of a set of key genes in cells derived from adult tissuesWhen a terminally differentiated cell in an adult body dies, it can typically be replaced from a stock of _____.proliferating precursor cells