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38 Cards in this Set
- Front
- Back
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When and where does meiosis occur?
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Meiosis occurs in the gonads and for males it starts in puberty, for females it starts before birth and freezes at prophase 1 where it where it continues after puberty and freezes at meiosis 2 where it completes at fertilization
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Why is the polar body smaller than the oocyte, what determines the position of the cleavage plane?
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oocytes need to have more cytoplasm to support two pronuclei during fertilization
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What experiments support the hypothesis that BPA causes anueploidy? Correlative or functional?
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increase in congression failure, plastic were extensively cleaned and by replacing it with new ones and the congression failure rate returned to normal, saw that bpa was much higher in damaged plastics, added bpa to water, congression failure increased. Functional, gain of function
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What structures characterize the mature oocyte?
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polar body and zona pellucida
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How can proteins in a cell be visualized?
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immunostaining/immunoflourescence
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What experimental evidence supports the hypothesis that the maternal and paternal pronuclei (genomes contained within) are not equivalent?
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Bipaternal and Bimaternal experiments both did not develop correctly at all, which suggests that both pronuclei are needed for different aspects in order to work
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How do early cleavage events in mouse or humans differ from zenopus?
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Its not equal size you see small cells, icm, surrounded by trophoblast
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How can you determine when a cell is specified?
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isolate and culture, see what it becomes. immunostaining
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What experimental evidence suggests that the blastomeres at the 4 cell stage in mouse are not equal
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there is evidence that shows the location of the blasotmere will determine its fate. SCMC may have some influence as well.
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Epigenetic
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coming from external factors and not internal ones
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Eed
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if present it marks x inactive chromosome
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If the male and female pronuclei essentially contain the same genes (genome equivalency), why do gynogenetic or androgenetic embryos not develop normally?
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Because they don't contribute equally, both the male and female pronuclei are necessary for normal development
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What role does the female genome play in embryo development? – support your answer with experimental evidence.
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Experiment with human cloning experiments by removing maternal genome and inserting a somatic cell which caused development to arrest at late cleavage states and transcriptional abnormalties in cloned embryoes . The only embryoes that survive to blastocyst stage had maternal genome present.
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If a mouse zygote contains only maternal pronuclei, how will the mouse embryo develop?What if there are only paternal pronuclei?
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bimaternal show strange organ development and bipaternal shows hydatidiform mole, trophoblast and placenta like tumors, usually are sporadic
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In the human somatic cell cloning experiment, is the cytoplasm of the oocyte or the contents of the oocyte pronucleus required for reprogramming the somatic cell nucleus?
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Provide experimental evidence to support your answer. Yes because the somatic cell nucleus transfer without time aressted in cleavage but if it spent time with the maternal genome it was able to go to blastocyst stage
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What experiments can be done to determine if a cell line is pluipotent?
Where will GFP-tagged Histone H2B be located in a cell? |
Oct4/sox2 expression, ssea tag, see if certain genes are repressed that, take cells and put them into an animal, they will form a teratoma and will have tremendous ability to differentiate. nucleus
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Expression of which genes would be characteristic of a pluripotent cell?
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Oct4/sox2
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In the compacted morula, how does the plane of cell division affect the fate of a blastomere?
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a cleave can result in trophectoderm and inner mass cell daughters, outer cells can contribute to inner cell mass
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What is the SCMC, and where is this protein complex localized in the oocyte, morula, and blastocyst staged mouse embryo?
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subcortical maternal complex deposited in egg as it matures, probably helps with polarity and cell division. Complex persists on the outside and may be responsible for specifying trophecctoderm.
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How does an epithelia differ from mesenchyme?
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Eptihelia are sheet like cells that act as units while mesenchyme cells are loose individual cells
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Why are proteins in the SCMC referred to as Maternal Proteins?
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because they come from the mom
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Why will all embryos from a mater+/- X mater +/- mating develop normally, yet none will survive if the female is mater -/- and the male is +/-?
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because the paternal x chromosome is silenced
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Where is Cdx2 localized in the compacted morula and blastocysts staged mouse embryos?
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in the hippo pathway, trophectoderm cells express it
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Which cells gave rise to the inner cells of the compacted mouse morula ( at 32 cell stage)?
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cells without SCMC
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How does the plane of cell division at the compacted morula stage influence the fate of the daughter cells?
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different types of cleavage in the morula determine daughter blastomere fate, parallel cleavage form trophectoderm, othogonal cleavage give rise to trophectoderm and either epiblast or primitive endoderm
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How does cell contact affect the localization of the SCMC? How does it affect expression/localization of Yap?
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its localized near plasma membrane and stays away from region where two cells come from together. Only surface cells will have the complex. SCMC sends a signal that represses the hippo pathway which allows YaP to connect with Tead which transcribes CDX2, a trophoblast cell. Supresses oct4 and sox2
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What are the functions of the Hippo pathway proteins (for example: kinases, transcription factor, co-transcription factors, receptors, ligands, etc).
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Hippo is a kinase that phosphorlyates Lats which phosphorylates YAP . Phosphoralated Yap gets shuffled to the proteosome and is degraded.
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What activates the Hippo pathway?
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Cell polarity, lack of SCMC
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How will an embryo develop if Yap, Lats, Hippo, or Tead4 are mutated? What tissues will develop and what genes will be expressed in these tissues?
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Yap mutation would cause cells to become ICM, mutation in Lats will cause icm to become trophectoderm and same with hippo. Tead 4 moutations would cause trophectoderm to become icm
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If Tead4 or Cdx2 are localized in the nucleus of a blastomere, how will this cell differentiate?
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it will become trophectoderm
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How will loss of function mutations in Lats affect localization of Yap or Tead4?
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It would increase yaps and tead 4 expression
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How will loss of function mutations in Lats affect expression of Cdx2 and differentiation of the blastomere?
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Cdx2 would be expressed and cell will differentiate into trophectoderm
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If Cdx2 is expressed in a blastomere, how will this affect expression of Oct4, Sox2, and Nanog? What will be the fate of the cell?
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oct4 and sox2 will be suppressed and would become trophectoderm.
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If gata6 is expressed in a blastomere, how will this affect expression of Nanog? How will this cell differentiate?
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Gata6 represses nanog and the cell becomes visceral endoderm
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11. What role does Nanog play in the inner cell mass cell? Provide evidence for your answer.
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Nanog represses Gata6 and turns ICM to epiblast. Experimenys nanog expression in icm but not in trophectoderm or primitive endoderm. You can see this with immunostaining. It seems to be used with pluripotent and multipotent.Other experiments show exclusiveness of nanog and gata6. Nanog will be reactivating genes for pluripotency and suppressing differentiation.
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What is X-inactivation, where and when does it occur?
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Silence the paternal x chromosomes in females. It occurs in early development, before cleavage. Imprinting is when paternal chromosomes are not expressed equally
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How can X-inactivation be monitored in the female embryo?
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Eed marks inactive xchromosome. Nanog is necessary for x chromosome reactivation by correlative evidence and functional evidence. Correlatively because nanog expressed cells showed no condensed x chromosome. Functional evidence ko nanog and x chromosome are not reactivated
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How does X-inactivation differ in somatic differentiated cells or cells that are “poised” for differentiation compared to pluripotent cells
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Xinactivated cells are not truly pluripotent while reactivated x chromosomes are in pluripotent cells
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