Cell determination and differentiation define how generic embryonic cells become specialized cells.
Determination is an irreversible commitment of a cell to having a particular function in the future. Before determination, the cell can become any cell type. It may occur due to the secretion of specific molecules from nearby cells. These molecules, also called morphogens, may cause nearby cells to follow a particular developmental pathway by expressing pathway-specific genes. The cell only becomes committed to a specific lineage after the determination.
A cell’s fate is determined by the specialized gene products that it produces. This includes changing the structure, function, and biochemistry of the cell to match the cell type through differentiation. For instance, if a cell commits to becoming a neural cell, it can differentiate to either neuron or neuroglia. Once it chooses neuron, it must carry out the specialized function of making neurotransmitters to transmit electrochemical impulses. Cells that have not yet differentiated, or which give rise to other cells that will differentiate, are known as stem cells.
Subsequently, cells can exist in tissue level. Similar cells that have a common function are grouped based on the four basic tissue types, namely epithelial, muscle, connective, and nervous tissue.
Each tissue type has a specific role in the body:
- Epithelium covers the body surface and lines body cavities.
- Muscle provides movement.
- Connective tissue supports and protects body organs.
- Nervous tissue provides a means of rapid internal communication by transmitting electrical impulses.
Practice Questions
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Key Points
• When a cell is determined, it is committed to a particular cell lineage.
• When the cell differentiates, it assumes the structure, function, and biochemistry of that cell type.
• Stem cells can differentiate into different cell types.
• Cells can exist in tissue level; the four basic tissue types are epithelial, muscle, connective, and nervous tissue.
Key Terms
Morphogens: a chemical agent able to cause or determine the origin and development of morphological characteristics
Tissue level: a community of similar cells that form a body tissue
Determination: an irreversible commitment of a cell to having a particular function in the future
Differentiation: the process during which young, immature (unspecialized) cells take on individual characteristics and reach their mature (specialized) form and function