Stem cells Flashcards
What are stem cells?
Undifferentiated cells- not adapted to any function
Stem cells are able to divide again and again, growth+ tissue repair
Once they specialise they enter the G0 phase of the cell cycle and are no longer able to divide
What is potency?
A stem cells ability to divide into different cell types
Totipotent- can differentiate into any cell type eg. zygote
Pluripotent- can form all tissue types but not whole organisms eg. early embryos
Multipotent- can form a range of cells within a certain type of tissue eg. haematopoietic cells in bone marrow
Why do blood cells have to be replaced?
Red blood cells have no nucleus and few organelles to maximise the capacity for oxygen
Therefore they have a short life span so are constantly replaced by the bone marrow
What are sources of stem cells?
Embryonic- present at a very early stage of embryo development (totipotent) after about 7 days they become pluripotent
Adult- present from birth for the rest of life. Found in the bone marrow, are multipotent. Can be harvested from the umbilical cord of newborns
Meristems (plants)- found in the tips of roots and shoots, also between phloem and xylem tissue, pluripotent
What are the ethical objections to the usage of stem cells?
Removal of stem cells from embryo results in the destruction of the embryo
Life begins at conception- destruction of embryos is murder
Does the embryo itself have rights? Who owns the genetic material that is being used for research?
Embryonic stem cells- pluripotent and umbilical stem cells are only multipotent (restricting their usefulness)
Adult stem cells do not divide as well and are more likely to have acquired mutations
