Stem Cells Flashcards
What can stem cells turn into?
self-renew into another stem cell
give rise to more specialized cell types
What enzyme to stem cells have that helps them live a long time?
telomerase
How do stem cells divide?
asymmetrically: one stem cell; one w/ ability to be differentiated
What is totipotency?
can turn into any type of cell
about 16 first cells in a zygote
What does pluriportent mean?
can give rise to all cells of embryo and then adult tissues
blastocyst
these are cells that are cultured and turned into diff things
What is multipotency?
ability to give rise to diff cell types of a given lineage
adult stem cells
What are founder stem cells?
fixed number of divisions –> set population –> gives rise to body part proportions –> size of final structures
controlled by short range signals
What are transit amplifying cells?
differentiated cell that leaves basal layer –> goes to layer above
divide frequently, but have limitted # of div. = part of strategy for growth control
What is divisional asymmetry?
stem cell divides into two cells: One stem; one w/ ability to differentiate
what is environmental asymmetry?
Stem cell divides into two identical stem cells –> environment can alter one daughter cell
What is the immortal strand hypothesis
original strand of DNA preserved in 1 daughter cell from generation to generation
bc don’t want to introduce mutations to new lines
For those who agree w/ immortal strand hypothesis, how does original strand keep going to a daughter cell if dna synthesis is semi-conservative?
Methylation
Where do you get embryonic stem cells?
from blastocyst stage of embryo
What is an embryonic stem cell’s potency and how can you use it?
pluripotent
can proliferate indefinitely in culture
When put back in blastocyst, integrates well w/ embryo (can make chimera)
What happens if you inject an embryonic stem cell at a stage later than you are supposed to?
If later than blastocyst –> won’t get right sequence of cues –> doesn’t differentiate right –> can become a tumor
What type of tumors can ES cells turn into?
What characteristics do these tumors have?
Tertomas
can differentiate into wide range of tissues
don’t have axis formation/incabable of generating body plan
What do you grow ES cells in?
Layer of fibroblast feeder cells
serum free medium
replace specific growth factors to either maintain as stem cells or start to differentiate
What are the advantages of ES cell therapies?
reliable, highly reproducible
induce dev of specialized cell types
solve rejection problems
What is the main difference btw es stem cells and adult stem cells?
Adult stem cells have restricted potency
Harvested cells retain properties of tissue they’re from
What are hematopoietic stem cells and where are they from?
From bone marrow
turn into platelets, RBCs, and WBCs
What are mesenchymal stem cells/ where are they from?
From bone marrow, adipose tissue, tooth pulp, and Wharton’s jelly
become connective tissues (fat, bone, liver, muscle, and nerves)
What is special about cord blood?
undifferentiated cells
No gene manipulation required
Immune rejection is a big problem when using what type of cells?
adult stem cells
How do you do somatic cell nuclear transfer?
nucleus from somatic cell + donor oocyte –> blastocyst –> ES cells isolated
What 4 transcription factors can induce adult somatic cells to exhibit properties of ES cells?
(NOLS) Nanog Oct4 Lin28 Sox2
How do you get TFs into somatic cells for iPS?
Use viruses (trying to use better techniques like crispr)
What are the main drawbacks of iPS
- low yield
- Not identical to ES Cells
- Have high potential to turn into teratomas
What is the ethical quandary with SCNT?
Created blastocyst could become a fully functioning organism
