We Come from Single Cells: From Gene Regulation to Stem Cells

The DNA from both of our parents comes together in the fertilized egg cell, the zygote. This single cell can produce the adult Homo sapiens with all the different cell types. This is quite amazing, as amazing as the evolutionary history of Homo sapiens. The process of cell division means each new cell has the same DNA content and yet many different cell types can be faithfully produced at the right place at the right time. Different cells have different genes switched on and off. Transcription of the gene is regulated at the promoter region. Transcription in eukaryotes is more complex because of the presence of nucleosomes. Small noncoding RNAs can be involved in epigenetic regulation of transcription. In adult humans, different types of cells can be derived from stem cells. An example of stem cells in adult humans is the pluripotent cells in the bone marrow producing different blood cell types. Pluripotent stem cells also occur in plant meristems. Embryonic stem cells as well as induced pluripotent stem cells from mature cells are used for in vitro pluripotency. Switching stem cells into different cell types is considered as well as stem cell-based regenerative medicine, organoids, and embryo models.