Summary OCR A/AS-Level Biology 2.6.8 Stem Cells

Stem Cells
What are Stem Cells?
 Stem cells are simply differentiated cells, meaning they have not matured and are
without specialised functions

Stem Cell Potency
 Potency is the varying ability of stem cells to differentiate into specialised cells
 Totipotent – can differentiate into all types of body and extraembryonic (placental) cells
 Pluripotent – cab differentiate into all types of body not extraembryonic (placental) cells
 Multipotent – can differentiate into various cell types within a related family of cells

Differentiation
 Differentiation benefits multicellular organisms
 They can live after individual cells die
 Specialised cells carry out specific functions better than unspecialised cells

Sources of Stem Cells
 In animals:
o Embryonic stem cells – totipotent or pluripotent – extracted from embryos
o Placental stem cells – totipotent– extracted from placenta
o Adult stem cells – multipotent – extracted from adult bone marrow
 In plants:
o Meristematic tissue - pluripotent

Uses of Stem Cells
 Potential to cure many illnesses such as: type 1 diabetes; Parkinson’s disease;
Alzheimer’s disease; cancer; heart disease; spine diseases; leukaemia; arthritis; anaemia

Stem Cell Ethics
 Embryos can be considered alive humans and are killed in the process
 Extraction of embryonic stem cells pose a risk to female donors
 Placental stem cells are not enough to treat adults and cannot be renewed