stem cells

Question 1

what are stem cells?

Answer 1

cells that have the ability to make more cells like themselves
can differentiate - become other cells

Question 2

define totipotency

Answer 2

the ability to produce a full formed, complex multicellular organism
= fertilised egg, contains the genome that determines the ultimate structure

Question 3

what are terminally differentiated cells?

Answer 3

cells at the end of the development pathway

Question 4

pathway of cell differentiation

Answer 4

stem cell can either self-renew or produce precursor cells
proliferating precursor cells further divide a limited number of times to produce terminally differentiated cells

Question 5

how is stem cell differentiation controlled?

Answer 5

requires extracellular signals between stem cells and other cell types –> generate the right number of differentiated cells in the appropriate place

Question 6

what are embryonic stem cells?

Answer 6

pluripotent stem cells (derived from the inner mass of a blastocyst) that give rise to all somatic cell types in the embryo

Question 7

what is the wnt pathway?

Answer 7

a signalling mechanism in charge of adult stem cell maintenance, tissue homeostasis and embryonic development
when active, stem cells proliferate
(eg. in the intestinal crypt)

Question 8

how does the wnt pathway work in the intestinal crypt?

Answer 8

Wnt proteins are secreted by cells around the crypt base, especially the Paneth cells
–> sustains stem cell population

Question 9

what are iPS cells and why are they important/useful?

Answer 9

induced pluripotent stem cells
produced without the use of embryos – used to study/treat genetic disease

Question 10

how are IPSCs produced from a patient?

Answer 10

skin biopsy to extract an individual’s fibroblasts
add specific transcription factors (eg. Oct4, Sox2) to produce individual-specific IPS cells (they have been reverted to an embryonic-like state)

Question 11

explain two ways IPS cells can be used to study / treat genetic disease

Answer 11

Genetic correction: IPS cells genetically corrected, induced to differentiate in culture then transplanted back to patient

Drug screening: IPS cells induced to differentiate, study disease mechanism and screen for therapeutic compounds. patient can be treated with drug