Cell Differentiation Flashcards
What is differentiation?
changes in what proteins are expressed on cell (determined by gene expression)
which determines how the cell reacts to the outside world
Give an overview of the steps involved in differnetiation
Stem cell
Progenitors
Terminal functional cell
What are stem cells
what is the first stage in differentiation
undifferentiated cells that can self renew
upon being given a specific signal go through commitment and start to differentiate
are pluripotent
Progenitors step in differentiation
Some genes are turned on activated and some are deactivated
this is known as commitment can now only produce a limited new cell types (multipotent)
Terminal functional cells
permanently differentiated cells
only divide into identical cells (unipotent)
are unable to further differentiate
What is potency?
scope and ability of a cell to differentiate into another cell type
How is differentiation controlled
Through transcription factors
and
Extracellular signals
Role of transcription factors?
Specific transcription factors bind to specific promoter region upstream of the gene to be transcribed or in other effector regions further upstream of the gene
this can inhibit or activate genes and thus determine whether RNA Polymerase II actively transcribes the genes to produce mRNA
Transcription factors are specific and will lead to the expression or inactivation of certain specific genes and thus determines what proteins are produced and therefore what the cell becomes
Role of Extracellular signals
bind to specific receptors on specific cells which leads to an intracellular signal transduction cascade that leads to TF production and eventual binding to promotor regions of DNA leading to gene augmentation or suppression
EPO example
When blood O2 levels are low EPO is produced and secreted by the kidney
EPO travels in systemic circulation to bone marrow and binds to specific receptors on hematopoetic stem cells
intracellular signal transduction leading to a cascade of reaction leads to binding of TF to promoter region of DNA that codes for eurthroycte proteins
increased eurothrocyte production increase in blood O2 levels
Clinical therapies?
Induced cell programming is possible can force transcription factors to be produced in cells and lead to production of specific cells
can also undo differentiation in some cell to produce stem cells that can be used to produce any other body cell of that individual
Disease?
when differentiation goes wrong there is disease
B cell acute lymphoblastic leukaemia cells are stuck in a progenitor phase
accumulation of these progenitors and thus leading to formation of tumours
