6.5 : Stem Cells Flashcards
Define undifferentiated
Cells that are not adapted to any particular function and have the potential to differentiate.
Define potency
A stem cells ability to differentiate into different cell types
What are the different types of potency ? Give examples
Totipotent : can differentiate into any type of cell. Eg fertilised egg, zygote
Pluripotent : can form all tissue types but not whole organisms. Eg cells in early embryos
Multipoint : can form a range of cells within a certain type of tissue. Eg Haematopoetic in bone marrow
Define stem cells
A renewing source of undifferentiated cells
Where do erythrocytes and neutrophils come from?
Although they have different functions, all blood cells are derived from stem cells in bone marrow
What are the sources of animal stem cells?
Embryonic stem cells : thee cells are present at a very early stage of embryo development. They are totipotent. After a blastocyst has formed, the cells are now pluripotent.
Tissue ( adult ) stem cells : found in specific areas eg bone marrow. They are multipotent. Stem cells can also be harvested from the umbilical cord of newborn babies.
What are the advantages of getting stem cells from umbilical cords?
Plentiful supply
Invasive surgery not needed
Can be stored in case they are ever needed in the future
No rejection
What are the sources of plant stem cells?
Present in meristematic tissue. This is found wherever the plant is growing eg shoots and roots ( apical meristems )
Also located between phloem and xylem tissues ( vascular cambium ).
These are pluripotent.
What are the potential uses of stem cells?
Heart disease : muscle tissue in heart damaged. Tried experimentally with some success.
Type 1 diabetes : immune system destroys insulin - producing cells in pancreas. Tried experimentally with some success.
Parkinson’s disease : symptoms ( shaking and rigidity ) caused by death of domaine - producing cells in brain - drugs only delay progress of disease
Alzheimer’s disease : brain cells are destroyed due to build up of abnormal proteins - drugs only alleviate symptoms
Macular degeneration : causes blindness in the elderly and diabetic. Scientists currently researching use of stem cells - early results = encouraging
Birth defects : scientists have already successfully reversed prevailing untreatable birth defects in model organisms such as mice.
Spinal injuries : scientists have restored some movement to the hind limbs of rats with damaged spinal cords using stem cells.
What are stem cells already being used for?
Treatment of burns : stem cells grown on biodegradable meshes can produce new skin for burn patients
Drug trails - potential new drugs can be tested on culture of stem cells
Developmental biology - the study of the changes that occur as multicellular organisms grow and develop form a single cell ( eg unfertilised egg )
What are the ethics involved with stem cells?
The removal of stem cells from embryos normally results in the destruction of embryos.
Religious and moral objections : many people believe life begins at conception and therefore the destruction of embryos in murder.
