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Developmental Biology > Stem Cells > Flashcards

Stem Cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q
  1. why must germ cells be highly plastic?
  2. what do the primordial germ cells give rise to?
  3. where do the primordial germ cells arise?
  4. how are germ cells specified? (2 methods)
A
  1. because they must be able to give rise to all the cell types of a new organism
  2. gametes
  3. at the very edge or just outside the embryo
  4. autonomic specification or conditional specification.
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2
Q
  1. what is autonomic specification?
  2. in C ellegans, give an example of a cell lineage that is produced by asymmetrical division
  3. Where is Q2 found?
  4. What type of divisions does Q2 undergo? What does this produce/maintain
  5. What do P granules contain? give an example and its role
A
  1. specification of cells using cytoplasmic determinants with no environmental influence
  2. P cell lineage
  3. posterior end of the embryo
  4. meridional. produces 2 identical daughters, which maintains the stem cells
  5. specific cytoplasmic determinants such as PIE-1, which blocks all transcription in the cell so that it can’t differentiate.
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3
Q
  1. in drosophila, where is the posterior pole plasm found?
  2. what does the pole plasm mediate.
  3. name a pole plasm factor.
  4. What is the phenotype of mutants of this pole plasm factor?
  5. in frogs, where is the germ plasm restricted?
  6. Name a germ plasm factor
A
  1. posterior most cells
  2. the blocking of transcription so that cell division doesn’t occur
  3. germ cell less
  4. sterile
  5. vegetal pole
  6. nanos
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4
Q
  1. what is conditional specification?
  2. how is conditional specification of germ cells similar to autonomous specification? How does it differ
  3. where are primordial germ cells formed in the human? Why is this beneficial?
A
  1. specification influenced by signals from surrounding cells
  2. cytoplasmic factors block gene expression thus differentiation; the cytoplasmic factors are induced by surrounding signals
  3. formed in the extra-embryonic epiblast. here they are protected from the vast number of differentiating signals that are setting up the body axis.
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5
Q
  1. a combination of what (2) drives the migration of primordial germ cells
  2. what cells migrate along with them? What do these cells do, and how?
  3. How do PGCs migrate in drosophila?
  4. How do PGCs migrate in frogs?
  5. what pathway is followed in the migration of frog and human PGCs?
A
  1. chemoattractive and chemorepulsive cues
  2. support cells which maintain the protective niche by secreting SCF
  3. migrate passively with endoderm during germ band extension
  4. they migrate from the dorsal lip of the blastopore where they are specified through the developing gut, before leaving the gut to migrate to the gonads
  5. fibronectin and Sdf-1 (chemoattractant produced by gonads)
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6
Q
  1. mutations in what can lead to the development of tetromas?
  2. what are tetromas?
  3. what do tetromas contain?
  4. how do they form?
A
  1. any component involved in PGC migration
  2. encapsulated nonseminomatous germ cell tumours which contain tissue components that resemble normal derivatives of more than 1 germ layer
  3. contains many types of differentiated cells
  4. becuase they are unable to migrate properly, they tend to settle in the gut. Here they are exposed to many differentiating factors therefore will differentiate abnormally.
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7
Q

name 2 reasons as to why the use of embryonic stem cells in regenerative medicine is “dying out”

A
  1. ethical problems. If left alone, it has the potential to develop into a human
  2. tissue rejection - doesn’t overcome the fact that the cells are coming from someone else.
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8
Q
  1. are differentiated cells mitotic or not?
  2. Why must RBCs be replenished?
  3. where are RBCs replenished from? Why?
  4. Name another group of cells that often have stem cell niches and why?
A
  1. not mitotic
  2. because they lack a nucleus therefore have a short half life
  3. replenished from the bone marrow which contains a pool of multipotent stem cells
  4. cells which are exposed to harsh environments (such as skin and gut) as they are frequently damaged/destroyed.
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9
Q
  1. in what state are most adult stem cells found in?
  2. How is the above state governed?
  3. When do cells come out of the above state?
  4. what occurs when cells leave this state?
A
  1. a state of dormancy
  2. by epigenetic changes that make the cell transcriptionally inactive
  3. when exposed to certain signals
  4. they undergo a number of symetrical divisions to increase the size of the pool (self renewal) before differentiating.
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10
Q

name 3 roles of adult stem cells

A
  1. aging
  2. to maintain cell populations (cellular homeostasis)
  3. to aid healing
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11
Q
  1. where do adult stem cells reside?
  2. what does this environment do?
  3. name 3 things that can lead to stem cell activation?
  4. what can aberrant stem cell activation lead to?
A
  1. stem cell niche
  2. fosters the growth of resident stem cells
  3. mutations in stem cells, mutations in the signals the stem cells recieve, mutations that cause changes in the stem cell niche
  4. unregulated proliferation leading to cancer.
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12
Q
  1. what are haemopoetic stem cells?
  2. give 4 examples of myeloid cells
  3. give 3 examples of lymphoid cells
  4. where are haemopoetic stem cells found (3)?
A
  1. adult stem cells which give rise to all blood cell types
  2. erythrocytes, platelets, monocytes, macrophages
  3. B cells, T cells, NK cells
  4. bone marrow, placental tissue, umbilical cord
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13
Q
  1. give 6 cell types produced from mesenchymal stem cells
  2. where are they located?
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3. what do neural stem cells give rise to?
  4. name 3 cell types produced from neural stem cells
A
  1. chrondrocytes, myocytes, adipocytes, tendons, ligaments and connective tissue
  2. throughout the body
  3. neural projenitors
  4. neurons which migrate to the olfactory bulb; neurons involved in memory formation; neurons which contribute to energy/feeding circuits
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14
Q

TRACHEA TRANSPLANT

  1. where were adult stem cells taken from?
  2. what was used as a scaffold?
  3. why is this treatment preferred over standard transplantation?
A
  1. healthy part of trachea
  2. stripped down cadaver trachea
  3. no problems with rejection as the cells used to grow the trachea were the patients own.
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15
Q

Mammalian Gut Crypt

  1. where in the crypt are stem cells found?
  2. where in the crypt are differentiating cells found?
  3. what is each stem cell surrounded by?
  4. what is the name of the active stem cells? What occurs to these cells as they migrate?
  5. Name 3 morphogen gradients expressed in the crypt and how they influence stemness.
  6. how do (Q3) maintain stemness
  7. full activation of Stemness requires what?
A
  1. distal end
  2. proximal end
  3. paneth cells
  4. transit amplifying cells. they differentiate as migrating out of the crypt
  5. Wnts, notch and BMP; Wnts and Notch are expressed at high levels at the proximal end and BMP at low levels at the proximal end. High Wnt expression leads to the induction of LGR5
  6. produce high levels of EGF, Wnts and delta so that stem cells are constantly exposed to high levels of these factors
  7. R-spondin.
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16
Q
  1. describe how crypt stem cells can be separated from other cells using a FACs machine
  2. what structure is formed from a single stem cell?
  3. What is the organisation of this structure?
  4. How can these structures be used to treat bowel cancer?
A
  1. LGR5 is labelled with fluorescence with GFP; crypt cells are dissociated from one another; cells are passed through the machine, and sorts cells that fluoresce (stem cells) from those that dont
  2. organoid, with budding structures that resemble crypts
  3. perfectly organised containing stem cells, paneth cells, TA cells and differentiated gut cells
  4. to restore absoptive function of the wound bed following gut removal. Organoids are inserted into the wound bed. Initially they form a flat epithelial sheet, followed by crypt reconstruction.
17
Q

name 6 possible uses of gut stem cells and mini organoids

A
  1. research for intestinal cancer
  2. research for intestinal differentiation
  3. research for epithelial function
  4. diagnosis of coeliac disease, IBS etc
  5. investigation of drug absorption
  6. potential regenerative therapy
18
Q
  1. what type of factors can reverse the differentiation process?
  2. how do they do so?
  3. what does this process produce?
A
  1. Egg factors
  2. de-repress TFs that were repressed during differentiation
  3. induced pluripotent stem cells.
19
Q
  1. where are egg factors present?
  2. how many genes are capable of re-programming the nucleus into a pluripotent cell?
  3. how were these genes identified?
A
  1. cytoplasm of the egg
  2. 4
  3. developmental biology studies
20
Q

name 4 ways in which the use of iPS cells are exciting

A
  1. they have the ability to differentiate into many different cell types
  2. they are vastly renewable
  3. they are easily accessable (e.g take skin cells)
  4. individual specific (no immune rejection)
21
Q

describe how iPS cells could be used to treat parkinson’s/alzheimers

A
  1. cells are taken from the patients body and used to generate iPS cells
  2. the iPS cells are used to grow specialised cell that the patient needs (e.g neurons). As these cells are technically the patients’ own, they will not be rejected.
22
Q

Name 4 barriers that need to be overcome before iPS cells can be widely used

describe the potential uses of the lung on chip (2)

A
  1. the use of harmful oncogenes as part of the reprogramming factors
  2. hte use of viral vectors for gene delivery that carries the risk of insertional mutagenesis
  3. low efficiency
  4. lack of robust and reliable protocols for iPS differentiation
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  5. growing mini organs to study lung tissue function without needing to take it from an animal
  6. used to test effects of environmental toxins/drugs on lung tissue.

Developmental Biology (10 decks)

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