B.6B_CellSpecialization_Approaching – 03

 

To understand the process, let us look at the journey that a red blood cell (RBC) takes from start to finish. The life of a RBC, like cells in most multicellular organisms, begins with a fertilized egg cell. The fertilized egg divides to form two identical cells. After a few rounds of cell division, a small cluster of identical cells forms. The cluster is simple and not well organized.

After a few more cell divisions, the cells in the cluster differentiate and become more organized. Some become stem cells. Stem cells are cells that can form into many different types of cells. The location of stem cells in the germ layers is important. The red blood cells will come from cells in the bone marrow or spleen of most animals.

 

At the right time, stem cells will differentiate into more specific stem cells. One type will go on to form muscle tissue. A different type will form bone. A very specific type of stem cell will form blood cells. These stem cells will form in the bone marrow or spleen. They will continue to divide to form many cells. They will differentiate at certain times to become the different types of blood cells. This is the finish line for the formation of the mature RBC.

In some plants, the fertilized egg divides to form two daughter cells of unequal size. The smaller cell divides to form two types of plant stem cell tissues. The type of cells they become is based on where the tissue is located. One type of stem cell tissue is found on root tips and shoot buds. It provides cells for the plant to grow longer. This is how roots, stems, leaves, and flowers grow. A second type of stem cell tissue is located along the lengths of roots and shoots. It provides cells for growth in thickness in woody plants. The bark of trees grows from this tissue.

Environmental factors can affect cell differentiation. The color pattern of a Siamese cat’s hair depends on enzymes that are sensitive to temperature. The enzymes are involved in pigment production. Exposure to toxic chemicals in the early stages can block chemical signals. This blockage can cause abnormal structures in developing offspring.

The development from a single fertilized egg to a multicellular organism is a complex and controlled process. Many cells arise from one cell due to cell division. But the organism is not just a bundle of the same cells. Different types of cells arise from a few identical cells during cell differentiation. The many different cells in the multicellular organism perform specialized functions as they work together to maintain the organism.