Final answer:
A terminally differentiated cell maintains its identity by preserving its unique genetic expression. Such cells do not frequently divide and have specialized functions, with gene expression regulated by transcription factors.
Step-by-step explanation:
To preserve its identity, a terminally differentiated cell must maintain its unique genetic expression. These cells, such as red blood cells and neurons, undergo a process called cell differentiation where they become specialized to perform specific functions. Unlike stem cells, terminally differentiated cells do not divide frequently, and once they reach the Go phase, they usually do not re-enter the cell cycle. Instead, they may either retreat to a state of dormancy (senescence), undergo programmed cell death, or in abnormal cases, progress into unregulated cell division, which can lead to tumors or cancers.
All cells in the human body contain the same DNA, but differentiation results from each cell type expressing only a subset of genes, determining its unique characteristics. This selective gene expression is regulated by transcription factor proteins that bind to DNA, either promoting or inhibiting the transcription of genes. This specific expression is crucial for maintaining the distinct identity of each cell type as they carry out their functions and is key to the organism's overall health and development.