Chapter 5: Stem Cells

Question 1

3 Methods that stem cells can divide

Answer 1

1) symmetrical
2) single stem cell asymmetry
3) Population asymmetry

Question 2

symmetrical cell division

Answer 2

stem cell divides into eitehr 2 self renewing stem cells, or 2 daughte rcells that are committed to differentiate

results in expansion or reduction of SC population

Question 3

single stem cell asymmetry

Answer 3

stabilization of SC pop becaue one division results in 1SC and 1 daughter cell taht can differentiate

Question 4

population asymmetry

Answer 4

some SC in the population are more prone to produce differentiated progeny, while other SCs in the population divide symmetrically to maintain the stem cell pool.

Question 5

What stages will an embryo be totipotent

Answer 5

zygote up to 8 cell stages. These calls can produce all CELLS. Totipotent cells can make both germ layers and extraembryonic cells.

Question 6

Plouripotent cells

Answer 6

capable of producing of a single lineage. Can be either embryonic stem cells or stem cells for extraembryonic structures.

Question 7

is a zygote pluri or totipotent

Answer 7

pluripotent

Question 8

T/F: Pluripotent cells can undergo infinite generations of self renewal

Answer 8

true .

Question 9

T/F Multipotent cells can undergo infinite generations of self renewal

Answer 9

false. There is a finite number of generatinos for self renewal. contributes to aging.

Question 10

____ SCS generate cells for that particular tissue type in which they reside

Answer 10

multipotent stem cells.

Question 11

2 fates of a multipotent stem cell

Answer 11

MP cells can either repliicate into another MP, or the original MP can mature into progenitor cells without needing to produce progenitory daughter cells.

Question 12

progenitor cells are aka

Answer 12

transit amplifying cels.

Question 13

T/F Progenitor cells are capable of unlimited self renewal

Answer 13

false. they only divide a few times before differentiating. cells of the progenitor pool can mature into different but related cell types.

Question 14

Precursor cell

Answer 14

formed by a progenitor cell of a particular lineage. Basically an immature already-differentiated cell: ex/ a UNIPOTENT stem cell: a precursor that generates only on cell type (ex/ spermatogonia).

Question 15

T/F Precursor cells are unipotent

Answer 15

true. They are still “potent” because they can divide and differentiate–even though they only mature into one specific cell type at that point.

Question 16

T/F: terminally differentiated cells are unipotent

Answer 16

false. they are not potent at all anymore because they are not mitotically active. Ex/ sperm do not divide by mitosis, but the spermatogonia precursors do.

Question 17

stem cell niche

Answer 17

the microenvironment that surrounds a stem cell. extracellular/environmental mechanisms lead to intracellular changes that regulate stem cell behaviour.

Question 18

5 methods of stem cell regulation

Answer 18

1) physical mechanisms: structural and adhesion factors in the ECM, causes differences in cell to cell or cell to matrix interactions. Subsequent cell density can alter mechanical forces, influencing stem cell beahviour.

2) chemical regulation: secreted proteins from neighboring cells can influence SC states.
- endocrine, paracrine, and juxtacrine mechanisms (ex/ tgfbeta paracrine factor stimulates ECM formation/collagen production, which later acts as a physical mechanism for stem cell regulation).

3) cytoplasmic regulation: as a SC divides, factors determining cell fate are either selectively partitioned to one daughter cell towards a specific fate. (ie/ asymmetric spreading of intracellular factors cause daughter cells to differentiate differently)
- asymmetric localization of cytoplasmic determinant.

4) transcriptional regulation: occurs through TF network to keep SCs in a quiescent state, not actively dividing, or active proliferative state. TFs can direct daughter cells towards a specific fate.
5) epigenetic regulation: chromatin will be different states of accesibility ( uncoiled vs highly coiled), acting to regulate gene expression that impacts stem cell behaviour and division.