Stem Cell Flashcards
Define stem cell
Stem cells have the potential to develop into many different cell types in the body during early life and growth.
Fate of a cell definition
The fate of a cell defines what a cell will become in the course of normal development
Potency of a cell definition
The potency of a cell describes the range of different cell types it can become.
The potency of individual stem cell decrease until their fate is determined.
Totipotent stem cell definition
Embryonic stem cells can be isolated by pre-implantation stage embryos and these cells can become all cell types in the body.
Determination definition
Determination implies a stable change as the fate of determined cells does not change. Determination is followed by differentiation.
Differentiation definition
Differentiation happens after determination. Determination involves a change in appearance and function.
Explain the link between stem cells and tissue renewal
In many tissues stem cells serve as a sort of internal repair system, dividing without limit to replenish other cells as long as the person is alive.
What is the difference between pre-implantation embryos’ stem cells and adult stem cells ?
Pre-implantation embryo’s stem cells are totipotent while adult stem cells are limited to differentiating into cell types of their tissue of origine.
Inductive interaction definition
The most straightforward way to make cells different is to expose them to different environments : signals from neighboring cells. This signal is limited in time and space so that only a subset of the competent cells - those closest to the signal -take on the induced character.
List the steps of induction interaction
1- a cell produces an inducer
2- diffusion of the inducer creates a concentration gradient
3- another cell receives many inducers (as another doesn’t) molecules that bind to many receptors
4- inducer binding results in transcription factors activation and their movement to the nucleus
5- transcription factors bind a promoter, activating gene transcription
6- the protein encoded by the gene stimulates cell differentiation
Asymmetric cell division definition
Cell differentiation can also arise as a result of asymmetric cell division : some significant set of molecules is divided unequally between sisters cells at the time of division
Mixed progeny
Some cells must generate a mixed progeny, including daughter cells that remain undifferentiated like their parent as well as daughter cell that differentiate.
General definition of stem cell
- is not terminally differentiated
- can divide without limit
- when it divides each daughter cell has a choice : remain a stem cell or embark on a course that commits it to its terminal differentiation.
- it is self-renewing
What is the difference between divisional asymmetry and environmental asymmetry ?
In divisional asymmetry any loss of stem cell is irreparable while in environmental asymmetry is more flexible.
Ex: new patch of epidermis when cells migrate to repair the destroyed epidermis.
Transit amplifying cell
Consists in the transit from a stem cell character to a differentiated character and amplifying the number of differentiated progeny that results from a single stem cell division
