Stem Cell Research Paper

2502 Words Feb 18th, 2012 11 Pages
BIO 1 Paper
Stem Cells Research

WHAT ARE STEM CELLS?

* Stem cells are biological cells found in all multicellular organisms, that can divide through mitosis and differentiate into diverse specialized cell types or can self renew to produce more stem cells. * In mammals, there are two broad types of stem cells: embryonic stem cells that are isolated from the inner cell mass of blastocysts, and adult stem cells that are found in various tissues. * In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenished in adult tissues. In a developing embryo, stem cells can differentiate into all the specialized cells, but also maintain the normal turnover of regenerative organs, such as
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Such cells can construct a complete, viable, organism. These cells are produced from the fusion of an egg and sperm cell. Cells produced by the first few divisions of the fertilized egg are also totipotent * Pluripotent stem cells are the descendants of totipotent cells and can differentiate into nearly all cells, i.e. cells derived from any of the three germ layers. * Multipotent stem cells can differentiate into a number of cells, but only those of a closely related family of cells. * Oligopotent stem cells can differentiate into only a few cells, such as lymphoid or myeloid stem cells. * Unipotent cells can produce only one cell type, their own, but have the property of self-renewal which distinguishes them from non-stem cells (e.g. muscle stem cells).

Figure 1. Potency Figure 2. How Stem Cells Work

Figure 1. Pluripotent, embryonic stem cells originate as inner mass cells within a blastocyst. The stem cells can become any tissue in the body, excluding a placenta. Only the morula's cells are totipotent, able to become all tissues and a placenta.

*Morula – a solid mass (an embryo) consists of a hundred or more cells

EMBRYONIC STEM CELLS VS. ADULT STEM CELLS

Embryonic Stem Cells

Embryonic stem cell lines (ES cell lines) are cultures of cells derived from the epiblast tissue of the inner cell mass (ICM) of a blastocyst or earlier morula stage embryos. A blastocyst is an

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