Although the field has advanced - spectacularly in some cases - this overview still seems useful. The original web materials were designed as a supplement to that class presentation. This overview section summarizes the class presentation. This topic was discussed in the BITN class, Fall 2003. Note that the "nuclear transfer" type of cloning actually does not clone the donor cell, but only its nucleus. Those working with DNA refer to cloning a gene - making many copies of it outside its normal environment. Some plants can reproduce from pieces of an old plant - a type of cloning. ![]() Some organisms, such as bacteria, normally reproduce by cloning they get bigger, then divide in two, producing two identical daughter cells. The general meaning is to make an identical copy of something. The word "cloning" has various meanings in biology. That same nuclear transfer procedure has been used in some procedures for making stem cells - specifically for making embryonic stem cells. The common form of cloning that is discussed involves "nuclear transfer" only the nucleus of the cell to be cloned is used, and it is transferred to an egg cell that has been deprived of its own nucleus. This is particularly a challenge if the cell used for cloning is already differentiated. In part, this requires that the cell used for cloning be able to revert to the "primitive" state typical of an egg cell - able to replicate and differentiate. Potentially, stem cells may be useful in replenishing missing or defective cell populations in an organism.Ĭloning (in this context) involves growing a new organism from a single cell of an old organism. Stem cells are cells that can replicate and can turn into any of some variety of cells. ![]() These specialized cells are typically unable to replicate much, if at all. A fertilized egg cell develops into a complete organism that egg cell has the capability to replicate - and to "differentiate" (change) into different kinds of specialized cells (e.g., heart and kidney). Both involve dealing with the progress of cells as an organism develops. Why are cloning and stem cells shown as one topic? Because they are closely related in some ways. That is, some people will say ESC and some will say ES cells. Note: usage varies as to whether the C is included with the abbreviation for stem cell terms. \)Ībbreviations: ESC = embryonic stem cell(s).
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