Stem-Cells--Thomas-A-Stewart-Secondary-School：干细胞托马斯斯图尔特中学课件

1 of 18 Boardworks Ltd 2011Stem CellsStem Cells2 of 18 Boardworks Ltd 2011Stem-Cells-Thomas-A-Stewart-Secondary-School：干细胞托马斯斯图尔特中学课件3 of 18 Boardworks Ltd 2011What are stem cells?Stem cells are unspecialized cells capable of developing into many different types of cell.Stem cells found in embryos are called embryonic stem cells and develop into all the different types of cell in the body.Adults also contain stem cells.These are found in small numbers in many organs,including bone marrow,brain,skin and muscle.What are stem cells?Stem cells4 of 18 Boardworks Ltd 2011Embryonic stem cellsAfter the eight cell stage,most of the embryonic cells become specialized and can no longer differentiate.Some will become nerve cells,others will become blood cells,muscle cells,bone cells,etc.Up until the eight cell stage,all of the cells in a human embryo are identical.At this stage,these stem cells are unspecialized and can therefore differentiate into many different types of cell.nerve cellsred bloodcellscardiac musclecellsEmbryonic stem cellsAfter the 5 of 18 Boardworks Ltd 2011Adult stem cellsAdult stem cells are found in small numbers in many organs and tissues,such as bone marrow.Research has shown that some adult stem cells can be manipulated to produce many different cell types(e.g.brain stem cells can make muscle cells).This is called plasticity.Adult stem cells normally maintain and repair damaged tissue,and,unlike embryonic stem cells,can usually only make a small number of cell types.For example,adult stem cells in the skin only normally form skin cells.Adult stem cellsAdult stem cel6 of 18 Boardworks Ltd 2011lxylem:these cells transport water and minerals up the stem from the roots to the shoots and leaves Plant stem cellsPlants also have stem cells.Plant cells can differentiate to form specific cells throughout the plants life.Animal cells lose this ability early in their life cycle.Unspecialized plant cells are found in tissues called meristems.Plant stem cells can become specialized to form tissues such as:lphloem:these cells transport sugars,produced in the leaves,up and down the stem.These new types of tissue can be found in the flowers,leaves,stems and roots of the plant.xylem:these cells transport w7 of 18 Boardworks Ltd 2011Stem cells true or false?Stem cells true or false?8 of 18 Boardworks Ltd 2011Stem-Cells-Thomas-A-Stewart-Secondary-School：干细胞托马斯斯图尔特中学课件9 of 18 Boardworks Ltd 2011Super starfish!What do plants and starfish have in common?Chop the stem of a plant and it will grow back.Whats more,the cut stem can grow into a completely new plant.The same is true of the starfish!If it loses an arm to a predator,it will grow back.Even better,if the predator manages to eat everything but the arm,a new individual can grow out of the remaining arm!Super starfish!What do plants 10 of 18 Boardworks Ltd 2011Animal regenerationWhy can a starfish regenerate missing limbs?Humans and most other animals cannot do this,but scientists are studying how stem cells could be used to create new tissue and even new organs to treat disease,injury and conditions such as paralysis.The starfish contains stem cells that can divide,differentiate and produce new tissues to replace those that are lost.What type of stem cells should be used?Animal regenerationWhy can a s11 of 18 Boardworks Ltd 2011A controversial source?Most stem cell research has used cells obtained from embryos left over from fertility treatment.These are called embryonic stem cells(ESCs)and are the most powerful type because they can turn into any type of cell.Their use in research is strongly criticized by people who believe it is unethical to kill embryos for their cells.Work involving embryonic stem cells is subject to government regulation.A controversial source?Most st12 of 18 Boardworks Ltd 2011If you ran the countryIf you ran the country13 of 18 Boardworks Ltd 2011Therapeutic cloningTherapeutic cloning14 of 18 Boardworks Ltd 2011How could adult stem cells be used?How could adult stem cells be 15 of 18 Boardworks Ltd 2011Advantages of using adult stem cellsAdult stem cells are not as powerful as embryonic stem cells,but they do have other advantages.lThey come from volunteers so they are more ethically acceptable.lThey are less likely to become cancerous.lA patients own stem cells could be used to treat their own disease,avoiding the problem of immune rejection.There is a great deal of research into using adult stem cells to treat diseases.They could reduce the need for organ transplants,which have long waiting lists.lIt might be easier to guide their development into specific cell types.Advantages of using adult stem16 of 18 Boardworks Ltd 2011Stem-Cells-Thomas-A-Stewart-Secondary-School：干细胞托马斯斯图尔特中学课件17 of 18 Boardworks Ltd 2011GlossaryGlossary18 of 18 Boardworks Ltd 2011Multiple-choice quizMultiple-choice quiz