Exam 4 Lecture 43 stem cells Flashcards
Qualities of stem cells
- Are NOT terminally differentiated
- Can continue to divide without limit
- Are self-renewing (i.e., one of the daughter cells remains as a stem cell)
What special capability do stem cells have?
They can regenerate tissue over a lifetime
Potencies of stem cells (5)
totipotent, pleuripotent, multipotent, oligopotent, unipotent
totipotent
Can make every kind of cell
pleuripotent
Can make almost any kind of cell
multipotent
Can make multiple but limited cell types
oligopotent
Can make a few cell types
unipotent
Makes only one kind of cell
Transit amplifying cell
daughter cell destined for differentiation
When does transit amplifying cell divide?
It may divide multiple times before differentiation. It often divides more rapidly than a step cell.
Animal body plans are generated from
Embryonic stem cells
Regeneration and renewal of tissues/body parts depends on
Adult stem cells
Two types of asymmetric cell division
Intrinsic (divisional) and extrinsic (environmental)
Intrinsic asymmetry
Involves segregation of certain molecules to one side of the cell so that resulting daughter cells receive unequal amounts of those molecules
Why internal polarity in stem cell
Asymmetrical distribution of molecules within cell
centrosomes and intrinsic asymmetry
Distributed asymmetrically to daughter cells
Younger centrosomes causes differentiation
Stem cell niche
microenvironment around stem cells that provides support and signals; regulates self-renewal and differentiation
Why might some cancer cells survive radiation?
May be slowly dividing stem cells
Transit amplifying cells
From stem cells and divide a discrete number of times. Progeny differentiate.
ABC transporters
Pump drugs out of cells. Cancer cells may have a lot of these, so can avoid medication.
Why are cancer stem cells resistant to anti-cancer to drugs?
abc transporter and low rate of cell division
Oct4 and Sox2
Transcription factors that function in maintaining pluripotency in both early embryos and ES cells
c-Myc and Klf4
Transcription factors that modify chromatic structure so that Oct4 and Sox2 can bind to their target. c-Myc controls cell proliferation.
Producing induced pluripotent stem cells (iPS)
Transcription wave 1 Activate OSKM expression Differentiated fibroblast Loss of fibroblast specific marker protein Transcription wave 2 Gain of embryonic marker protein Endogenous OCT4 gene switched on
