6.5 Stem cells Flashcards
what are totipotent stem cells
> Divide and produce any type of body cell and can make a whole organism eventually
in development they translate only part of their DNA resulting in cell specialisation
only occur for limited time in early mammalian embryos
what are pluripotent stem cells
found in embryos
> become any type of cell but can make a whole organism
> used in research to treat human disorders
> sometimes don’t work or stem cells continually divide to create tumours
what are multipotent stem cells
found in mature mammals
> can divide to form a range of cells within a certain type of tissue
> multipotent cells in bone marrow can differences into limited number of cells
whats differentiation
the process of becoming specialised it involves the expression of certain genes but not others in a genome
why does stem cells activity have to controlled
as if they divide too fast that can lead to the forming of a mass of cells called a tumor which can lead to cancer but if cells divide too slowly then tissues arent replaced efficiently and this leads to aging
whats a stem cells potency
a measure of its ability to differentiate
what is the division of stem cells like
they are able to divide again and again but once they become specialised the go into G0 a permenent state of rest
what are all blood cells derived from
stem cells in the bone marrow
what type of stem cells are embryonic stem cells and when
they are totipotent stem cells and are present in the early stages of embryo development after about 7 days they form a mass of cells called a blastocyst and they are now pluripotent (and remain in this state until birth
what type of stem cells are tissue/ adult stem cells and when and how can they be harvested
they are multipotent they are present throughout life from birth and are found in specific areas eg bone marrow. they can be harvested from the umbilical cord of new born babies this is non invasive, theres a large supply and they wont be rejected by their owner at a later date in life
what type of stem cells are plant stem cells and when
they are pluripotent and are present in meristematic tissue, this tissue can be found wherever theres a growth occuring in plants eg, roots or shoots and its found between the phloem and the xylem
what are the uses of stem cells
> research and medicine
repairing damaged tissue
treatment of
neurological conditions eg Alzheimer’s and Parkinson’s
research into developmental biology
what are the ethics surrounding the use of stem cells and what alternatives are there
- removing stem cells from an embryo usually destroys the embryo
- moral obligations some view this as murder
- umbilical cords can be used but their multipotent while embryonic stem cells are pluripotent
- plant stem cells can be used
