干细胞研究ppt课件

1、Stem Cells in BiologyAn Introduction to Stem Cells and Stem Cell Applications for English Learners Andrew CreamerObjectives Define and describe the characteristics of embryonic and adult stem cells Describe the origins of various stem cells Describe the debate surrounding and identify misconceptions

2、 about stem cell research Describe the present and future applications for stem cell researchWhat makes a cell a stem cell? Plasticity: A stem cell is plastic, meaning it can develop into another type of cell. Differentiation: The process where a stem cell specializes or develops into another type o

3、f cell. Self-Renewal: a stem cell can divide (renew itself) indefinitely (go through mitosis) and without always developing into another cell.differentiatedcell Self-renewalStem CellCellStemDifferentiationDifferentiationQuickTime and aTIFF (Uncompressed) decompressorare needed to see this picture.st

4、/info/basics/basics4.aspImage courtesy of NIH resource for stem cell researchMajor Types of Stem Cells Embryonic Stem CellsTotipotent : cell can develop into all cell types“Immortal: can self-renew indefinitelyPlentiful Adult Stem CellsMultipotent: cell can develop into a few cell typ

5、es but not allLocated in few organs or may be unidentifiedHard to findEmbryonic Stem cells Embryos are formed in labs that help couples get pregnant. An egg and sperm fertilize a zygote and are inserted into a womans uterus to develop into an embryo and then fetus. QuickTime and aTIFF (Uncompressed)

6、 decompressorare needed to see this picture.biodidac.bio.uottawa.ca/thumbnails/filedet.htm?File_name=HUMN150B&File_type=GIFIn Vitro Fertilization (IVF): a sperm fertilizes an egg in a lab dish creating the embryo. QuickTime and aTIFF (Uncompressed) decompressorare needed to see this picture.en.w

7、/wiki/Image:Icsi.JPGEmbryonic Stem Cells This process creates multiple embryos that will not be used to make a baby. Many donors wish to donate these unused embryos to scientific research instead of having the lab throw them /wiki/Polar_bodiesFirst stages of segmenta

8、tion of a mammalian ovum. Semidiagrammatic. z.p. Zona striata. p.gl. Polar bodies. a. Two-cell stage. b. Four-cell stage. c. Eight-cell stage. d, e. Morula stage.Embryonic Stem Cells The embryo used in research is 4-5 days old and is a microscopic ball of about 150 cells. The ball as thick as a hair

9、 is called a Blastocyst and has three layers called germ layers. Each layer has special stem cells that makes a part of the body.QuickTime and aTIFF (Uncompressed) decompressorare needed to see this /wiki/Image:Blastocyst.svgBlastocyst: Source of Embryonic Stem CellsQuickTime

10、 and aTIFF (Uncompressed) decompressorare needed to see this /wiki/Image:Blastocyst%2C_day_5.JPG Blastocyst under the microscopeGerm Layers The embryo develops three germ layers of cells called the ectoderm, mesoderm and endodermQuickTime and aTIFF (Uncompressed) decompressor

11、are needed to see this /wiki/Image:Gastrulation.pngEmbryonic Stem Cell These embryos not used in IVF will not grow into a fetus or baby because an embryo like the one in the picture needs to be implanted inside a womans uterus to develop into a human fetus. Fetuses and babies

12、 are not aborted for stem cell research.QuickTime and aTIFF (Uncompressed) decompressorare needed to see this picture.AuthorPhotograph by Ed Uthman, MD.PermissionPD Public /wiki/Image:Tubal_Pregnancy_with_embryo.jpg.Embryonic Stem Cells Embryos can also be used for cloning rese

13、arch. The process called Somatic Nuclear Transfer (SNT) removes an embryos nucleus and replaces it with another persons adult cell nucleus. The embryo would then have the ability to develop into a clone or genetic copy of the nucleus donor if the embryo were implanted into a womans uterus.QuickTime

14、and aTIFF (Uncompressed) decompressorare needed to see this /wiki/Image:Icsi.JPGDolly the Sheep was first cloned using SNT. An adult sheep body cell nucleus was implanted into an embryo and then implanted in a mother sheeps uterus.QuickTime and aTIFF (Uncompressed) decompress

15、orare needed to see this /wiki/Image:Dollyscotland.JPGAdult Stem Cells Adult stem cells are called somatic or body stem cells. Some people call these adult because they are found after an embryo develops into a fetus and are no longer an embryonic stem cell. Not only adults h

16、ave adult stem cells! Some organs are believed to lack stem cells and these cells grow and replace dead cells with /wiki/Image:Mitosis-flourescent.jpgAdult Stem Cells Adult stem cells develop into a few cell types. These multipotent cells are used in bone-marrow transplants a

17、nd will develop into all the blood cells. These cells are important, but some organs may not have adult stem cells and these cells can be difficult to find. QuickTime and aTIFF (Uncompressed) decompressorare needed to see this picture.ulb.ac.be/sciences/biodic/homepage2.htm red corpuscles figurelAll

18、 Stem Cells Are Important All stem cells can help scientists learn how cells regenerate or repair injured cells, tissues and organs. Scientists need both types of stem cells for their research. Each cell type can help inform scientists on how we develop and how some diseases affect our cells.Stem Ce

19、ll Debate Some people oppose stem cell research because they believe that the 4-5 day old ball of cells is a living human being. What some do not understand is that unused embryos are trashed regardless. Many people, religious and non-religious, believe it is better to use these embryos for research

20、 on how to cure human diseases rather than to just trash them without purpose. The underlying issue is the personal belief when life actually begins.Misconceptions Pregnancy, fetuses or babies are aborted or harmed in stem cell research. Fact: Fertilized Blastocysts donated from IVF labs are used an

21、d no pregnancy is aborted. The fertilized embryos are removed from womens bodies and used for research. Fact: The embryos are left over from IVF and are frozen and are not implanted for pregnancy.MisconceptionsA clone is grown in a lab without an embryo or born from a mother and is the same age and

22、personality as you, and has no belly button.Fact: a clone would need a fertilized embryo and would have to be implanted in a womans uterus. If you were cloned at 14, the clone would be 14 years younger than you (a baby you) and would have to have a mother to be born, so yes, it would have a belly bu

23、tton.QuickTime and aTIFF (Uncompressed) decompressorare needed to see this /wiki/Image:Femnavel.jpgMisconceptions If the embryos were not used in stem cell research they would have been used to make children. Fact: The embryos left over from IVF are discarded. Men and women w

24、ho donate their embryos do not know that their embryos are used for research. Fact: The embryos used in scientific research are donated with written and informed consent (permission) by the donors.Stem Cell Research Some scientists want to identify the genes and processes used in embryo development

25、to figure out how to make new cells in damaged or diseased cells and organs or fix old cells by reprogramming them to be young cells again.QuickTime and aTIFF (Uncompressed) decompressorare needed to see this picture.Cell-Based T/info/basics/basics6.aspCell-Based Therapies Sci

26、ence has known for a long time that certain organisms and organs can regenerate or re-grow themselves after being damaged or injured. For example, planaria can regenerate after being cut up into small pieces and certain lizards can regenerate limbs and tails. Scientists want to know “How do they do it? and study these animals in the lab. Using cells to medically regenerate or replace dead or injured cells is an example of a cell-based therapy. Planaria can regenerate lost cellsQuickTime and aTIFF (Uncompre