pack 4- stem cells Flashcards
stem cell
an undifferentiated cell that can give rise to other specialised` cell types. no limit to divisions.
totipotency
undifferentiated stem cell can give rise to all specialised cell types, all switched on
pluripotency
undifferentiated stem cell can give rise to most specialised cell types, some genes witched off
multipotent
undifferentiated cell which can only give rise to specialised cell types of a closely related family, many genes switched off
embryonic stem cell
zygote and 8 cell embryos- totipotent
inner cell mass of blastocyst- pluripotent
umbilical cord stem cells
umbilical cord blood/ placenta- pluripotent or multipotent
adult stem cells
bone marrow
brain/connective/skin/liver cells = multipotent
plant stem cells
totipotent
uses of stem cells
replace dead or damaged cell/ repair damaged tissue
produce tissues or organs for transplants
treat diseases - eg heart disease, type 1 diabetes
theraputic cloning
nucleus removed from egg cell
diploid nucleus placed in egg cell
new cell stimulated to from a balstocyst
pluripotent stem cells removed
develop into tissues/organs identical to patient
used for transplant.
adv- tissue not rejected
induced pluripotent stem cells
adult somatic cells genetically reporgammed to be pluripotent - forced to express genes important for properties of embryonic stem cells
HFEA
Decide max age of embryo for research
check source of stem cell
stop human cloning
stop unnecessary repeat research
ensure institutions have a license
adult stem cells- disadvantages
multipotent
give rise to small range of tissues
difficult to get
very few in body
embryonic stem cells- disadvantages
ethical issues
risk rejection, infection or cancer
induced pluripotent stem cells- disadvantages
difficult to create
difficult to control differentiation- cancer
