IB Biology Topic B2.3: Cell Specialization Key Definitions

Differentiation is the process where pluripotent cells (unspecialized cells) develop into specialized cells with unique structures and functions.

A stack of flattened, membrane-bound sacs that process, package, and distribute proteins and lipids.

Hematopoietic stem cells (HSCs) are immature cells that can develop into all types of blood cells.

Mitochondria are double-membrane-bound organelles responsible for producing ATP through aerobic respiration.

Multipotent stem cells are more limited than pluripotent cells. They can differentiate into several related cell types, but their potential is more restricted.

Contractile units within muscle cells, composed of actin and myosin filaments that allow for muscle contraction.

Pluripotent stem cells can differentiate into any cell type of the embryo (i.e., all three germ layers - ectoderm, mesoderm, and endoderm) but cannot form extra-embryonic tissues (like the placenta).

Pneumocytes, also known as alveolar cells, are specialized cells that line the alveoli in the lungs. They are responsible for exchanging oxygen and carbon dioxide, which is vital for respiratory function.

A stem cell niche is a microenvironment within a tissue that supports stem cells by maintaining their self-renewal, survival, and differentiation potential.

Stem cells are undifferentiated cells with the unique ability to divide endlessly and differentiate into various specialized cell types.

Surfactant is a lipid-based substance that reduces surface tension in the alveoli, preventing the alveoli from collapsing after exhalation.

A large cell-like structure formed by the joining together of two or more cells

These are the most potent type of stem cells, meaning they have the ability to differentiate into any cell type in the body, as well as extra-embryonic tissues (such as the placenta). They can form an entire organism.