chapter 6 - stem cells

what are stem cells

undifferentiated cells with the ability to differentiate into specialised cells

why do stem cells divide by mitosis

to create more undifferentiated cells

what is stem cell potency

the range of cells that a stem cell can differentiate to

higher potency = larger amount of different types of cells it can differentiate too

what are the 4 types of stem cells

totipotent

pluripotent

multipotent

unipotent

what is a totipotent stem cell and name an example

stem cell which can differentiate into any type of cell

>zygotes are totipotent they can differentiate into embryonic aswell as extra-embryonic cells (make up the placenta) that go on to form the foetus, creating a whole organism

what is a pluripotent stem cell and name an example

stem cell which can differentiate into any type of cell but CANNOT form the whole organism

>embryonic stem cells AFTER 7 days will form a blastocyst, a mass of cells so are now pluripotent

why is a blastocyst not totipotent

because after roughly 7 days the embryo will have divided various times and will not be able to form extra embryonic cells (forming the placenta) so cannot form a whole organism

what is a multipotent stem cell and name an example

stem cell which can differentiate into a limited range of cells

>haematopoietic cells which can differentiate into various types of blood cells

what is a unipotent stem cell

stem cell which can only differentiate into one type of cell

what are the 2 sources of stem cells in animals

embryonic stem cells

adult stem cells

when are embryonic stem cells present & give adv. and disadv. of usage

only during early stages of embryo development

adv: greatest potency they are pluripotent & can be taken from fertility treatments when they are no longer needed for research

disadv: ethical issues, killing a potential life

when/where are adult stem cells present & what type of stem cells are they

throughout life found in bone marrow and umbilical cord

-multipotent and pluripotent

what is an overall disadv of using stem cells

as they have the ability to divide indefinitely, if this division becomes uncontrolled it can lead to cancer

name 2 uses of stem cells and examples of how they’re used

to repair damaged tissue e.g. pancreas cells to treat type 1 diabetes

to treat neurological conditions e.g. alzheimer’s

what are iPSC and give an advantage

induced pluripotent stem cells which are stem cells that have been genetically modified

>less chance of rejection

what is the sources of stem cells in plants

meristematic tissue

where is meristematic tissue & what type of stem cells are they

wherever growth is occurring e.g. roots or shoots

>pluripotent

what is another name for meristematic tissue and where is it found

between the xylem and phloem tissue known as vascular cambium, it will differentiate into these types of tissues when required