Chapter 1.1, Problem 1QC

Summary Introduction

To explain: The reason why the process of differentiation is essential to specialization with an example.

Introduction: Differentiation and specialization of cells occur during development of the organisms. Cellular differentiation occurs during development wherein the cells differentiate from one cell type to another with the aid of molecular cell signaling. The process of cellular specialization makes the cell become specialized for a particular function.

Explanation of Solution

The cell can specialize only if the cell differentiates. During development, the cells are first formed by rapid mitosis called as cleavage. During which the growth phases do not occur. The process of differentiation is reversible, provided the essential cell signaling factors are available, but the process of specialization is irreversible. Once the cell is specialized, its fate is fixed, and the cell will perform the respective set of functions until death. Cell specialization occurs as part of division of labor between cells. The cells are assigned a particular set of functions.

The embryonic cells first multiply rapidly to form several cells. The cells acquire new characteristics that cause several specific changes within the cell. This process is called as cellular differentiation. Only if differentiation occurs in immature cells, the cells can specialize. Thus, differentiation is the first and foremost process for specialization to occur. Therefore, the process of differentiation is essential for specialization to occur.

Example:

Specialization of red blood cells begins from the gastrula. The following are the steps involved in the specialization of cells to form the erythrocytes:

1. 1. The blastula forms the gastrula.
2. 2. The mesodermal cells of the gastrula differentiate to form the hematopoietic stem cells that are multipotent.
3. 3. The hematopoietic stem cells differentiate into common myeloid progenitor cells that are also multipotent.
4. 4. The common myeloid progenitor cell specializes into unipotent stem cells called as proerythroblasts.
5. 5. The proerythroblast specializes into erythroblasts.
6. 6. Erythroblast undergoes various changes and forms several intermediate cells; the nucleus is expelled and finally forms the reticulocyte.
7. 7. The reticulocyte specializes into erythrocyte in the blood stream.

The cells that differentiate give rise to several cell lineages, but the cell that specialized can give rise to only one cell lineage.

Conclusion

As the cells must differentiate first in order for the cells to specialize, the process of differentiation is essential for specialization.