chapter 20 Flashcards
multicellular organisms
have many specialised cells
all originate from undifferentiated stem cells
what are stem cells?
undifferentiated cells that can continually divide to form specialised cells
the process by which they become specialised- differentiation
totipotent stem cells
can divide and form any type of body cell
during development, they translate only part of their DNA, resulting in specialisation
occur for limited time only in mammalian embroys
pluripotent stem cells
can differentiate to form almonst any type of cell
used in research, prospect of using them to treat human disorders
replace burnt skin cells
neurones for people with parkinson’s disease
beta cells for people with type 1 diabetes
found in the inner mass of a blastocyst
issues with using pluripotent stem cells in research
treatment does not work
cells divide uncontrollably to form tumour
ethical issues with using theraputic cloning
is it right to make a clone of yourself to make an embryo, extract the stem cells and then destroy the embryo.
multipotent and unipotent
found in mature mammals
can divide to form a limited number of cell types
multipotent can differentiate into limited number of cell types
unipotent stem cells can only differentiate into one type of cell.
sources of each type of stem cell
pluripotent stem cells
can be found in embryos, up to 16 days after fertilisation
umbilical cord blood, placenta, bone marrow- contain multipotent stem cells
stem cells in the bone marrow
can be used to repair those in a tissue/organ
iPS cells/induced pluripotent stem cells
created artificially in the lab by reprogramming a patients own stem cells.
created from adult somatic/body cells by using appropriate protein transcription factors
unipotent adult stem cells are returned to state of pluripotency
similar to embryonic pluripotent stem cells but without ethical issues of destroying an embryo
adult can consent to use.
