Stem Cell
A stem cell is an undifferentiated cell capable of self-renewal and differentiation into specialised cell types. Stem cells are found in embryos (embryonic stem cells) and adult tissues (adult stem cells), serving as a repair and replenishment system throughout life. Their unique plasticity makes them central to regenerative medicine, disease modelling, and therapeutic research.
Types of Stem Cells and Their Properties
| Type | Source | Potency | Example Use |
|---|---|---|---|
| Totipotent | Fertilised egg (zygote) | Can form entire organism | Early embryo development |
| Pluripotent | Inner cell mass of blastocyst | All body cell types | Disease modelling |
| Multipotent | Bone marrow, cord blood | Related cell lineages | Blood cell production |
| Induced Pluripotent (iPSC) | Adult somatic cells reprogrammed | Pluripotent-like | Personalised therapy |
| Unipotent | Muscle satellite cells | Single cell type | Muscle repair |
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Related Terms
Cell Cycle
The cell cycle is the ordered sequence of events by which a cell grows, replicates its DNA, and divides into two daughter cells. It consists of interphase (G1, S, and G2 phases) and the mitotic phase (mitosis and cytokinesis). Precise regulation of the cell cycle through checkpoints is essential for normal development; dysregulation leads to cancer and other diseases.
Apoptosis
Apoptosis is a form of programmed, genetically regulated cell death that occurs in multicellular organisms as a normal and controlled part of development and homeostasis. It is characterised by cell shrinkage, chromatin condensation, membrane blebbing, and fragmentation into apoptotic bodies that are cleared by phagocytes without triggering inflammation. Dysregulation of apoptosis is implicated in cancer (insufficient apoptosis) and neurodegenerative diseases (excessive apoptosis).
Gene
A gene is a specific sequence of DNA (or RNA in some viruses) that encodes the information required to produce a functional product, most commonly a protein or functional RNA molecule. Genes occupy defined loci on chromosomes and are the fundamental units of heredity, transmitted from parent to offspring. The modern molecular definition encompasses not only coding sequences (exons) but also regulatory elements such as promoters and enhancers that control when, where, and how much a gene is expressed.
From Old English "stemm" (trunk of a tree) + Latin "cella" (small room). The term reflects the concept of a foundational cell from which diverse cell lineages branch, analogous to a trunk giving rise to many branches.