Stem Cells Flashcards
What are the 4 characteristics of stem cells
- Not terminally differentiated
- Can divide w/o limit
- Undergo slow division
- when divide gives rise to 1 cell with stem cell characteristics, the other cell must be w/ the ability to be differentiated
What is a totipotent cell
A cell w/ the ability to give rise to embryotic and extraembryonic. Ex. a zygote
What do extraembryonic tissues support
These are cells that support embryonic development
What is a pluripotent cell
A cell w/ the ability to give rise to all cells of the embryo and then adult tissues
What is multipotency
A multipotent cell has the ability to give rise to different cell types of a given lineage (adult stem cells)
How is the amount of somatic cells per location dictated
Each tissue has a fixed number of founder cells depending on the proportion of the body part. These founder cells are programmed to have a fixed number of divisions and are controlled by short-range signals that operate for a few hundred cell diameters.
What is a strategy for growth control
Transit amplifying cells
What are transit-amplifying cells
They are cells that divide frequently and are a strategy for growth control because they only have a finite number of divisions.
what are 2 ways we maintain a steady pool of stem cells
- Divisional Asymmetry
2. Environmental Asymmetry
What is the difference between environmental and divisional asymmetry
In divisional, you are guaranteed a stem cell. In environmental, the environment may influence one of the 2 stem cells to make it into a differentiated cell
How do stem cells differentiate
In stages of differentiation, there are multiple factors that combine to produce EPIGENETIC markers in the cells DNA that restrict DNA expression, so they can only differentiate into certain cells.
what is the immortal strand hypothesis
Instead of randomly segregating their DNA in mitosis, the adult stem cell will segregate asymmetrically to give the terminally differentiating cell (non-stem cell) the strand that’s more likely to mutate.
“By retaining the same set of template DNA strands, adult stem cells would pass mutations arising from errors in DNA replication on to non-stem cell daughters that soon terminally differentiate (end mitotic divisions and become a functional cell). Passing on these replication errors would allow adult stem cells to reduce their rate of accumulation of mutations that could lead to serious genetic disorders such as cancer.”
What is the stem cell hierarchy
Totipotent embryonic stem cell
Pluripotent embryonic stem cell
Multipotent stem cell
Pros/Cons of embryonic stem cells
Pros: Develop into different cell types, indefinite proliferation in culture, can integrate well with an embryo if put back into a blastocyst
Cons: Unrestricted development potential, can cause tumors, on their own ES are not capable of generating a body plan (can lead to teratomas)
How can we dictate was an embryonic stem cell will differentiate into
Cultured embryonic stem cells can be placed into a culture with various growth factors (retinoic acid, macrophage colony-stimulating factor, dibutyryl cAMP, fibroblast growth factor) to make various tissues (adipocytes, neurons, macrophages, smooth muscle, astrocytes, etc.)
