Chapter 8 Cell differentiation & Stem Cells Flashcards
If you remove the meiotic spindle from an unfertilized egg, the you place a somatic cell next to it, and shock it with electricity, the nucleus will go into the unfertilized egg. The environment of the unfertilized egg can restructure the DNA to form a zygote, which gives rise to all cell types.
If a somatic cell can give rise to any cell type, then the somatic cell has not lost any genetic material from the code. The difference in terms of DNA therefor must be a regulatory. So we know that differential cell types are achieved through differential expression
Stem cells are critical for the maintenance and repair of tissues.
Most tissues will have a stem cell line that maintains the population of cells within the tissue (example : epithelial tissue does this)
It is sometimes possible to chemically induce a somatic cell to induce embryonic like stem cells.
This is generally done by chemical factors found within cells. In theory there are likely molecules within the unfertilized egg that can restructure epigenetic regulation in a significant enough matter to allow a zygote to arise (since cloning works)
Master regulators:
A gene which leads to activation of a broad series of genes once turned on. Sometimes a master regulator gene actually exists. More often however several genes work together to perform a regulatory cascade, and the correct factors must be present to activate each gene type in order to triger a regulatory cascade.
Traditional single master regulatory cascade example :
the gene eyeless, which is therefor important in formation of an eye. Because those without this gene are eyeless. You can induce expression of eyeless in a imaginal disc which is fated to become leg tissue and you will see eye formation on the leg.
so if expression of eyeless causes leg tissue to become a full formed eye, what must that mean.
It means that eyeless is a master regulator furthermore eyeless is a conserved master regulator as the same transcription factor product, but from a mouse ortholog still induces formation of an eye in the leg tissue of a fly. So the mechanisms are the same.
Myoblasts are what?
A myoblast is determined to become a muscle cell, but it has not differntiated. Cells which are determined can often still proliferate, and indeed if myoblasts are cultured in growth factor then they will continue to divide.
