2.6 Stem Cells Flashcards
what are stem cells?
unspecialised cells that can divide by mitosis and potentially differentiate into any type of cell during development
give examples of where stem cells can be found:
embryos
umbilical cords
bone marrow
what is potency?
a stem cells ability to differentiate into different cell types
the more cells it can differentiate into the greater it’s potency
what are totipotent stem cells?
can differentiate into any type of cell they have the potential to form a whole organism
what are pluripotent stem cells?
can form all tissue types but not whole organisms
what are multipotent stem cells?
only form a range of cells within a certain type of tissue
how do cells become specialised?
certain genes are expressed, the rest are switched off
where are totipotent stem cells found?
zygotes
after 7 days a blastocyst forms and the stem cells become what?
pluripotent
when are tissue stem cells present?
from birth
give an example of where tissue stem cells are found:
bone marrow
tissue stem cells are what type of stem cell?
multipotent
give examples of where multipotent adult stem cells can be found:
liver pancreas umbilical cord spinal cord bone marrow skin blood
adult stem cells are multipotent and can be triggered to become what?
pluripotent
why are stem cells found in umbilical cords useful for research?
in plentiful supply
non invasive
can be stored
where is plant meristematic tissue found?
tips of roots and shoots where growth is occurring
between xylem and phloem - known as vascular cambium
what can cells from the vascular cambium do?
differentiate into xylem and phloem
what is the potency of the plant stem cells?
pluripotent (remain pluripotent throughout a plants life)
what is a RBCs average life span and why?
120 days
lack of organelles & nucleus (akaryotic)
stem cells in the bone marrow produce how many RBCs per kg of body mass per day?
3 billion
how long do WBCs live?
6 hours
how many WBCs does bone marrow produce?
1.6 per kg per hour
when does the no. of WBCs the bone marrow produces increase?
during infection
what are the stem cells in the bone marrow called?
haematopoietic stem cells
the ability of stem cells to differentiate means they have the potential to do what?
be transplanted and replace damaged tissues
what often happens as a result of a heart attack? what could stem cells do?
muscle tissue becomes damaged
stem cells could be used to replace the damaged tissue (has been tried experimentally with some success)
what happens to a persons beta cells in type 1 diabetes?
the bodys immune system attacks them so they don’t produce insulin
what do stem cells have the potential to do in type 1 diabetes?
create new insulin producing cells
what happens in Alzheimer’s disease?
nerve cells dies interrupting the interconnections of the cortex (involved in memory, personality and behaviour) resulting in memory loss
how could stem cells be used to treat Alzheimer’s ?
grown into nerve cells to replace those that have died in the brain repairing the damage of Alzheimer’s
what happens in Parkinson’s disease?
death of dopamine producing cells in the brain resulting in shaking & trembling
how could stem cells be used to treat Parkinson’s?
using stem cells to create new dopamine producing cells
with research into stem cells and Parkinson’s what problem has arisen?
producing enough reliable dopamine producing cells
which stem cells show the greatest promise for treating parkinsons?
embryonic - totipotent
which stem cells is it not possible to treat Parkinson’s with currently?
adult stem cells
what is macular degeneration?
macula of the retina (light sensing nerve tissue at the back of the eye) deteriorates causing blindness in elderly & diabetics
how could stem cells be used to treat macular degeneration?
replace the deteriorating nerve tissue
what have scientists already done using stem cells, in rats & mice?
reversed birth defects
restored movement in some with damaged spinal chords
what does gene therapy involve?
inserting healthy genes into a cell to replace faulty ones in the hope of treating a disease
why would stem cells be beneficial in gene therapy?
they have the ability to self renew so the need to provide repeated administrations of gene therapy would be reduced
stem cells are used in developmental biology to help us understand more about what?
developmental disorders & cancers
stem cell use has the risk of what?
rejection of foreign tissue grown from stem cells by the patient’s immune system
risk of developing tumours & cancers
what is an issue of the use of embryo’s for stem cells?
removal of stem cells results in the destruction of the embryo (religious & moral issues)
where are embryos used for stem cell research from?
left over from IVF
law changes mean embryos can be created in a lab as a source of stem cells
embryonic stem cell transplantation carries the risk of tumour formation why?
during normal growth, cell division & specialisation follow a set program which can be affected when stem cells are taken, cultured & transplanted
why are adult stem cells and umbilical chord stem cells restricted in usefulness?
they are multipotent and are more likely to mutate
What are many drugs in medicine derived from?
Plants
Plant stem cells can be cultured leading to what?
An unlimited supply of cheap plant based drugs
What is paclitaxel and what is it used for?
Common drug used in treatment of lung & breast cancer obtained from bark of yew trees
Why is the supply of paclitaxel limited?
Trees have to be mature
Recently stem cells of the yew trees have been used to do what?
Produce the drug cheaply in sustainable quantities
Why do us of plant stem cells face few ethical issues?
Human life is not harmed in the process
