Stem cells and potency Flashcards
What are stem cells?
all cells in plants and animals begin as undifferentiated cells and originate from mitosis or meiosis
they are not adapted to any particular function (unspecialised)
they have the potential to differentiate to become any one of the range of specialised cell types in the organisms
What is the function of stem cells?
able to undergo cell division again and again
and are the source of new cells necessary for growth, development and tissue repair
once stem cells have become specialised they lose the ability to divide and enter the G0 phase of the cell cyckle
Why does the activity of stem cells have to be strictly controlled?
if they don’t divide fast enough then tissue are not efficiently replaced, leading to ageing
if there is uncontrolled division then they form masses of cells called tumours, which can lead to the development of cancer
What is stem cell potency?
the stem cell’s ability to differentiate into different cell types
the greater the number of cell types it can differentiate into the greater its potency
What does totipotent mean?
toti - total
stem cells can differentiate into any type of cell
a zygote and the 8 or 16 cells from its first few mitotic divisions are totipotent cells, which are destined to eventually to produce a whole organism
they can also differentiate into extra- embryonic tissues like the amnion and umbilicus
What does pluripotent mean?
pluri - plural - several
stem cells can form all tissue types but not whole organism
they are present in early embryos and are the origin of the different types of tissue within an organism
What does multipotent mean?
these steam cells can only form a small range of cells within a certain type of tissue
haemotopoetic stem cells in bone marrow are multi potent because this gives rise to the various types of blood cell
