Stem Cells

Question 1

Totipotent definition

Answer 1

Can form complete organism; present in embryo

Question 2

Pluripotent definition

Answer 2

Can form many tissue types but not complete organism; present in embryo

Question 3

Multipotent definition

Answer 3

Can form different types of cells within an organ but not a different organ or cell type; present in adults.

Question 4

Unipotent definition?

Answer 4

Can form only one type of cell; present in adults.

Question 5

What are the two types of stem cells used to grow lab stem cells?

Answer 5

Embryonic Stem (ES) cells and Induced Pluripotent (iPS) cells

Question 6

Where are ES cells sourced from?

Answer 6

Inner Cell mass in blastocyst and are pluripotent.

Question 7

Where are iPS cells from?

Answer 7

They are reprogrammed adult cells, and are pluripotent.

Question 8

When iPSCs and ESCs are cultured in a suspension form multicellular aggregates are called?

Answer 8

Embryoid Bodies

Question 9

How can ES cells be maintained as undifferentiated cells in a culture

Answer 9

• Requires conditioned medium that contains growth factors
  
  • Medium taken from irradiated fibroblast cells (cant divide)
• Extraceullar matrix proteins
• Inhibitory growth factor
  
  • Keeps cells undifferentiated
  • If LIF/gFGF removed ES cells form embryoid bodies.

Question 10

What are two inhibitory growth factors of ES cells

(One in mouse and one in human)

Answer 10

• Leukemia inhibitory factor (LIF) for mouse cells
• Basic fibroblast growth factor (bFGF) for human cells

Question 11

What transcription factors regulate pluripotency of ES cells?

Answer 11

• Oct4, Sox2, Nanog
  
  • each bind to own promoter and to other promoters
  • Can activate or repress genes.

Question 12

What transcriptional factors can be added to adult cells to form iPS cells?

Answer 12

Oct4, Sox2, Kfl4, c-Myc

Question 13

How did cloning of dolly occur, or GFP mice?

Answer 13

• Somatic Cell nuclear transfer:
  
  • Transfer of nucleus from adult cell into unfertilized egg.

Question 14

How does a niche function?

Answer 14

• Depending on the signals provided by neighboring cells, a microenvironment of stem cells can occur called a niche.

Question 15

How do stem cells differentiate in Drosophila germarium?

Answer 15

• Forms oocytes
• cap cells create niche by secreting Dpp, Gbb, Hh
  
  • These repress Bam (Differentiation factor)
• When the germ line cells divide:
  
  • one daughter remains adjacent to cap cell and stays germ-line stem cell
  • The other cell is too far away from Dpp, Gbb, and Hh, thus Bam turned on adn cell becomes cystoblast.
    
    • Cystoblast divides to form 16 cells
      
      • One of these cells becomes oocyte.

Question 16

How do stem cells differentiate in the intestine?

Answer 16

• Found in the crypt
• The cells divide and differentiate as they move up the villus
• Lgr5+ cell stem cell is found in the crypt.
  
  • The stem cell is maintained by Wnt protein secreated by niche cells.

Question 17

How do hematopoietic system cells differentiate?

Answer 17

• Forms red blood cells, platelets, and immune cells
• Liver provides niche in late embryonic development
• Bone marrow provides niche in adult.
• Hematopoietic stem cells found in umbilical cord blood

Question 18

What role does Wnt play?

Answer 18

Maintains stem cells in the intestine.

Question 19

What do cap cells secrete to create niches in drosophila and what do they repress?

Answer 19

Dpp, Gbb, Hh

Repress: Bam