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Flashcards in Stem Cells Deck (22)
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1
Q

What is a stem cell?

A

A cell that can either self-renew or give rise to more specialized cell types.

2
Q

Characteristics of stem cells (5)

A
  1. Not terminally differentiated.
  2. Can divide without limit.
  3. Undergo slow division.
  4. When it divides, it gives rise 1 cell with stem characteristics and 1 with the ability to be differentiated.
  5. Adult stem cells are tissue specific.
3
Q

Totipotency

A

Ability to give rise to all cells of an organism, including embryonic and extraembryonic tissues (placenta). Located in the zygote.

4
Q

Pluripotency

A

Give rise to cells that make up the body (embyronic cells). Located in the blastocyst.

5
Q

Multipotency

A

Give rise to different cell types of a given lineage (ex: cord blood cells can give rise to RBC, moncyte, and leukocyte). An adult stem cell. Located in various tissues.

6
Q

Founder stem cells (3)

A

Programmed to have a fixed number of divisions.
Controlled by a short range signals.
Define the size of large final structures.

7
Q

Transit amplifying cells (4)

A

Divide frequently.
Transit from a stem cell to a differentiated cell.
Programmed to have limited number of divisions.
Committed.

8
Q

Divisional asymmetry

A

Asymmetric division of cells, resulting in 1 with stem cell characteristics and 1 with factors that give it the ability to differentiate.

9
Q

Environmental asymmetry

A

Division makes 2 identical cells but the environment may influence/alter 1 cell.

10
Q

Immortal strand hypothesis

A

Daughter cells retain stem cell status and capability for long term renewal by selectively retaining original DNA.

11
Q

Embryonic stem cells (6)

A
Derived from blastocyst.
Can proliferate indefinitely.
Unrestricted developmental potential.
Can re-integrate when re-introduced to to blastocyst.
Develop into different cell types.
Can become a tumor.
12
Q

Teratoma

A

Germ cell mass containing cells from different sources (ex: hair, muscle, bone).

13
Q

Transcription factors responsible for maintenance of pluripotent stem cells in embryo (4 FONS)

A

FoxD3
Oct4
Nanog
Sox2

14
Q

Growth factors found in pluripotent cells (2 CG)

A

Cripto

GDF-3

15
Q

Problem with the application of adult stem cells

A

Harvested cells have memory of their original cell type; they cannot be coerced to become a cell of a different tissue. Experts believe adult stem cells cannot replace embryonic stem cells.

16
Q

Hematopoietic stem cells (HSCs)

A

Differentiated as blood components.

17
Q

Mesenchymal stem cells (MSCs)

A

Differentiated as connective tissues and organ tissue.

18
Q

Cord blood

A

Undifferentiated and does not require gene manipulation.

19
Q

Immune rejection

A

If adult stem cells are not genetically the same, the grafted cells can be rejected by the host. The host develops an immune reaction.

20
Q

Somatic cell nuclear transfer (SCNT)

A

Nucleus from somatic cell injected into oocyte of a donor, replacing the oocyte nucleus. Blastocyst from hybrid oocyte generated and ES cells isolated. Solves rejection ass because the cells will express the patient’s genes.

21
Q

iPS cells (induced pluripotent stem cells)

A

Recombinant DNA technologies used to develop pluripotent stem cells starting differentiated adult cells.

22
Q

Challenges of SCNT (2)

A
  1. Inefficient - may take hundreds of oocyes.

2. Technically demanding - needs to be available in many hospitals.