Final answer:
Stem cells are undifferentiated cells capable of limitless division and can differentiate into specialized cells under certain conditions. They have not yet developed their certain functions, which they gain through the process of differentiation guided by gene expression.
Step-by-step explanation:
Stem Cells and Differentiation
Stem cells are undifferentiated cells, meaning that they have not yet developed their certain functions. Unlike cells that have undergone the process of differentiation, stem cells have the unique ability to divide without limit and can, under specific conditions, differentiate into various specialized cells. Each cell type expresses only a subset of genes, determined by transcription factors, leading to the unique characteristics of that cell. Stem cells have a full protective cell membrane, a nuclear membrane, and a full set of DNA, but they lack a special function until they differentiate.
The ability to differentiate into specialized cells is what makes stem cells so vital in developmental biology. Their broad potential permits the development of different cell types within the human body through unique gene expression. Therefore, when stem cells are mentioned as undifferentiated, it implies that they have not yet acquired their certain functions required for specialized action.