Name __________________                          Developmental Biology | Spring 2012Part 1This external group of follicle ...
This structure contains microtubules, intermediate filaments and gives the cell itsstructure and aids in internal transpor...
Why do you think that during oogenesis polar bodies are formed to discardchromosomes rather than forming four haploid eggs...
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Developmental Biology, Assignment 1

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Developmental Biology, Assignment 1

  1. 1. Name __________________ Developmental Biology | Spring 2012Part 1This external group of follicle cells shares a name with a cloud formation These small finger like protrusions give a cell, or in some cases an organ moresurface areaThis "spot weld" works to hold cells together locallyIf you want to contain liquid within a membrane, would you want to use tight or gapjunctions?The blastocyst contains the Trophoectoderm and what other two components?What is a germline cell?How many chromosomes does each human parent contribute to their offspring?Which part of the human egg protects against polyspermy — Zona Pellucida, or theCumulus Cells?What is a somatic cell?This whip-like structure allows sperm to reach their "Final Destination"Which gamete looks more like an independent organism? Why do you think itsstructure is such?What is the function of capacitation in mammals?What general type of molecules in the cell wall send signals, allow passage throughthe membrane and act as markers?
  2. 2. This structure contains microtubules, intermediate filaments and gives the cell itsstructure and aids in internal transportPart 2Zulori discovers a new deep-sea, shrimp-like organism which is very small and hasa short lifespan, perhaps because it lives in nutrient-poor conditions. He names thisorganism deseshrilior and decides to investigate how it develops. In oneexperiment, Zulori separates the blastomeres at the 8-cell stage and finds that theyall develop into mature deseshriliors. What can Zulori conclude about the potency ofthese cells? Why?In another experiment, Zulori removes some of the cells closest to the blastocoel ina deseshrilior blastula. He then watches them grow in a petri dish with nutrients;after a number of divisions, these cells become neural stem cells. The removal of thesame cells and their implantation into a blastocyst or gastrula also results in theformation of neural stem cells from these cells. Are these cells specified ordetermined? Why?Upon further study with fluorescence microscopy, Zulori finds that the somatic cellsof mature deseshriliors have 24 chromosomes. Assuming that 24 is the diploidchromosome number for this organism, how many chromosomes should Zuloriexpect in deseshrilior gametes? Why?Suppose one of a male mouse’s spermatogonia has a mutation in its gene for theGalT protein, and this mutation changes the structure of GalT so it no longer bindsZP3. Will the spermatozoa that this spermatogonia gives rise to be able to do thefollowing? Why or why not?(a) Get through the hyaluronic acid surrounding an egg(b) Get through the zona(c) Fuse with the egg
  3. 3. Why do you think that during oogenesis polar bodies are formed to discardchromosomes rather than forming four haploid eggs from one oogonia (the way fourspermatozoa are formed from a single spermatogonia)?Listen to or read the NPR story “Study Suggests Way To Create New Eggs iInWomen” ( http://www.npr.org/blogs/health/2012/02/27/147344258/study-suggests-way-to-create-new-eggs-in-women ).(a) Based on what we have covered in this course, what kind of cells are the“primitive ‘stem’ cells hiding in the ovaries”? Why?(b) The Nature Medicine paper mentioned in this news story describes these cells as“mitotically active”. What might this suggest about the nature of these cells in vivo?(i.e. how might these cells live and grow in a human female?)(c) Why was it an important finding that these cells could not only become oocytesbut also be surrounded by a follicle?(d) Why do you think these findings are important? What do you envision as thepotential uses of this research?

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