Define ‘totipotent’
undifferentiated cells which can give rise to any specialised cell needed for an entire new organism
Define ‘pluripotent’
undifferentiated cells that can form most of the cell types needed for an entire new organism
Define ‘multipotent’
undifferentiated cells that can form a very limited range of differentiated cells within a mature organism
What type of cells are embryonic cells?
pluripotent - from blastocyte
What type of cells are adult/somatic stem cells?
undifferentiated cells found among the normal differentiated cells in a tissue/organ that can differentiate when needed to produce any one of the major cell types found in a particular tissue or organ
How do pluripotent stem cells from embryos provide opportunities to develop new medical advances?
can be used to:
-treat diabetes, multiple sclerosis
-replace damaged tissues e.g. nerve tissue
What are the ethical considerations in using embryonic (pluripotent) stem cells?
can save many lives but:
- unethical as embryos die when stem cells are removed
- risk of infection
- risk of rejection
- can cause cancer
After fertilisation, what do totipotent cells differentiate into?
totipotent
pluripotent in blastocyte
fully differentiated somatic cells
How do epigenetic modifications can result on totipotent stem cells - pluripotent - fully differentiated cells?
What is a fibroblast?
connective tissues
How can differentiated fibroblasts be reprogrammed to form iPS cells?
- fibroblasts taken from skin samples
- viruses used as vectors to introduce 4 genes for transcription factors to activate specific genes in adult cells to produce pluripotent cells
- cells behave similarly to embryonic stem cells
Which genes produce iPS cells?
Oct4
Sox2
Klf4
c-Myc
Why are the use of iPS stem cells less problematic than embryonic stem cells?
- no issue of rejection
- do not harm anything
but they are hard to grow and manipulate pluripotent stem cells
