cancer, stem cells and cancer stem cells Flashcards
what is a stem cell
a cell which can self-renew and differentiate
define self-renewal
cell can divide into exact copies of itself with the exact same properties
define differentiation
a permenant change in gene expression
what is asymmetric stem cell division
when the cell renews and differentiates at the same time (this happens ~80% of the time)
define totipotent
can make everything
define pluripotent
can make all somatic cells
define multipotent
can make many different cell types
define bi-/tri- potent
2/3 etc. cell types
define unipotent
can only differentiate into one cell type
what is potency restricted by
with developmental age/tissue restriction
what are the 2 types of stem cell
embryonic and adult (tissue) stem cells
what are the characteristics of embryonic stem cells
- they are cultured in vitro from cells in the early embryo
- pluripotent
- immortal (indefinently self-renew)
what are the characteristic of adult stem cells
- they exist in many tissues
- normally contribute to tissue maintenance
- numbers, properties and functions vary enormously
what are the characteristics of somatic stem cells
- rare
- slow cell cycle (divide infrequently)
- symmetric OR asymmetric cell division
- unspecialised
- present in many adult tissues
- usually respect germ layer boundaries
define regeneration
homeostasis + repair
where are stem cells densley populated
in tissues with a natural turnover (skin, blood etc)
why would you “reserve” stem cells
for injury repair (in muscle)
what is special about the liver
it can fully regenerate (no matter how much has been removed)
what is cancer caused by
mutations
what are somatic cells known for
being often short-lived and post-mitotic, because of their specialised function
what happens to mutations in long-lived, proliferating cells
they may accumulate - if a mutation occurs in a stem cellm all lineage from that stem cell will regenerate
what do stem cells divide to make
progenitor cells
(which have a much more rapid cell cycle, and so they expand their no. so that the stem cells that divide infrequently can lead to the maintenance of the many cell types it maintains)
what is the pathway from stem cell to specialised cell
stem cell - progenitor cell - transient amplifying cell - specialised cell
what happens when mutated stem cells divide
the daughter cells are also mutated
