Genetic Engineering - Cloning, DNA, Stem Cells Pros and Cons
Molecular genetics


The future technology

Stem Cells Introduction


(A) gut, (B) neural cells, (C) bone marrow cells, (D) cartilage, (E) muscle and (F) kidney cells.


A stem cell is an unspecialized cell that gives rise to a specific specialized cell, such as a blood cell. They have the ability to divide for indefinite periods in culture and to give rise to specialized cells.

They are best described in the context of normal human development. Human development begins when a sperm fertilizes an egg and creates a single cell that has the potential to form an entire organism. This fertilized egg is totipotent, meaning that its potential is total.

This cell begins to divide immediately. Approximately four days after fertilization and after several cycles of cell division, these totipotent cells begin to specialize, forming a hollow sphere of cells, called a blastocyst.

The blastocyst has an outer layer of cells. Inside the hollow sphere, there is a cluster of cells called the inner cell mass.

The inner cell mass cells will go on to form virtually all of the tissues of the human body. Although the inner cell mass cells can form virtually every type of cell found in the human body, they cannot form an organism.

These inner cell mass cells are pluripotent — they can give rise to many types of cells but not all types of cells necessary for fetal development.

The pluripotent stem cells undergo further specialization into stem cells that are committed to give rise to cells that have a particular function. These more specialized stem cells are called multipotent.

While stem cells are extraordinarily important in early human development, multipotent stem cells are also found in children and adults.

Adapted from: http://www.ncbi.nlm.nih.gov/About/primer/genetics_cell.html

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