Unit 18: Stem Cells Flashcards

(41 cards)

1
Q

what is totipotency?

A

ability to form a fully formed, complex, multicellular organism

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2
Q

what are the requirements to be a tissue?

A
  1. mechanical strength (connective tissues)
  2. delivery of oxygen and nutrients and removal of waste (blood vessels)
  3. electrical signaling (nerve cells)
  4. disposal of dead and damaged cells (macrophages, lymphocytes)
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3
Q

which cells originate outside the tissue and then invade it during development?

A

nerve cell axons, endothelial cells, schwann cells

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4
Q

which cells originate outside the tissue and then invade it continuously?

A

macrophages, other blood cells

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5
Q

what are the 3 factors contributing to tissue stability?

A
  • cell communication
  • selective cell adhesion
  • cell memory
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6
Q

what is cell memory?

A

when cell preserve their distinct identity and pass it onto their progeny

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7
Q

what is selective cell adhesion?

A

homophilic binding and other selective attachments keeping cells in their proper place

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8
Q

how long does it take for intestinal cells to renew?

A

3-6 days

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9
Q

how long does it take fornerve cells to renew?

A

trick question they NEVER do

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10
Q

what do osteoclasts do?

A

slowly eat away old bone matrix

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11
Q

what do osteoblasts do?

A

deposit new bone matrix

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12
Q

how long does it take blood cells to be removed from bone marrow?

A

120 days

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13
Q

how long does it take for skin to be renewed?

A

2 months

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14
Q

what makes a cell terminally differentiated? give some examples.

A

unable to divide themselves.

red blood cells, epidermal cells in upper layers of skin, cells in gut epithelium

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15
Q

where do replacement cells come from for terminally differentiated cells?

A

proliferating precursor cells which come from undifferentiated stem cells

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16
Q

how can stem cells be identified if they are difficult to spot in tissues?

A

specific molecular markers

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17
Q

how do stem cells differentiate into the appropriate cell type?

A
  • express specific transcription regulators
  • developmentally restricted
18
Q

describe how cell replacement occurs in the lining of the small intestine?

A

we have stem cells at the bottom of crypts which give rise to precursor cells.

the precursor cells move upward in the epithelial sheet and then differentiate into absorptive/secretory cells

differentiated cells die when they get to the top of villi

19
Q

what are crypts?

A

epithelial tissue that descend down into underlying connective tissue

20
Q

describe cell replacement in the stratified epithelium epidermis?

A
  • the stem cells and precursor cells are attached to the basal lamina
  • differentiating cells travel outward from site of origin, perpendicular to cell sheet
  • terminally differentiated/dead cells are shed from kin surface
21
Q

what is hematopoiesis?

A

the process of forming many possible types of blood cells and platelets from one hematopoietic stem cell

22
Q

where are hematopoietic stem cells found?

23
Q

describe how Wnt proteins stimulate cell proliferation in intestine.

A
  • the signal molecule promoting proliferation is located in the crypt
  • crypt cells secrete proteins that prevent Wnt pathways outside the cell from being stimulated

when Wnt active, we get cell proliferation

24
Q

how do stem cells repair lost and damaged tissues?

A

proliferate indefinitely and produce progeny that differentiate

continuously renew normal tissues

25
how do we treat people with leukemia? what is this treatment analogous to in mice?
- iridate or give cytotoxic drugs that destroy the cancerous cells - bone marrow transplant gives the patient new hematopoietic cells - analogous to what we do when mice lose their hematopoietic stem cells
26
what does it mean when a cell is pluripotent?
can proliferate indefinitely while retaining ability for unrestricted differentiation
27
which cells give rise to all tissues and cell types in body?
embryonic stem cells
28
progeny ES cells integrate into whatever site they come to occupy, which means ____
they adopt the characteristics and behaviors of normal cells
29
mice ES cells are used to study what?
gene function and organism development
30
what are some issues that may arise from the use of ES cells to repair human tissues?
immune rejection - immune system can destroy these cells if they are genetically different ethical considerations - is the use of human embryos to produce ES cells ethical?
31
what are induced pluripotent cells (iPS cells)? what cells are turned into iPS cells?
differentiated adult cells that can be induced into an ES cell like state ex. fibroblasts
32
iPS cells can induce expression of what transcription factors?
Oct4, Sox2, Klf4
33
describe some cell-based therapies utilizing iPS and what condition they treat.
skeletal muscle fibers - muscular dystrophy nerve cells - parkinsons insulin secreting cells - type 1 diabetes cardiac muscle cells - heart attack
34
can iPS cells be used to study the potential effects of candidate drugs?
yes they can
35
how can iPS cells be used to treat individuals suffering from genetic illnesses?
take out fibroblasts from individual suffering from genetic disease, add Oct4, Sox2, Klf4 to make them iPS cells, repair the disease causing mutation, induce the cells' differentiation and put them back in!!!
36
how can iPS cells be used to study the potential effects of candidate drugs?
take out fibroblasts from individual, add Oct4, Klf4, Sox2 to make them iPS cells, let cells differentiate, add drug that reverses diseases to affected cells, give human the drug if it works out!
37
ES cells and iPS cells can be forced to differentiate and self assemble into what?
organoids
38
what are organoids?
miniature organs grown in lab resembling actual organs in terms of organization
39
human ES cells can form what type of organoid structure?
multilayered retina!
40
what is the most complex organoid to have been produced?
human brain
41
what is the purpose of organoids?
studying organ development by: - identifying/manipulating genes - exploring cell-cell interactions - how are developmental pathways impacted by disease?