Lecture 2 - Cell Differentiation & Neural Induction II Flashcards
totipotent/omnipotent stem cells
can give rise to any cell type + placenta
pluripotent stem cells
can give rise to any cell type but not the placenta
multipotent cells
can develop into a limited number of cell types in a particular lineage
Briggs & King Experiment (question)
do cells discard unneeded genes during cellular differentiation?
Briggs & King Experiment (hypothesis)
if not, terminally differentiated cells would still have all of the genes necessary to make any other type of cell
Briggs & King Experiment (test)
extract nucleus from skin cell in albino frog embryo and implant it in the center of wild-type frog egg that has been enucleated
Briggs & King Experiment (result)
some eggs began forming albino tadpoles that eventually formed adult frogs
Briggs & King Experiment (conclusion)
as cells become differentiated into specialized cells, they retain all genes needed to make any type of cell
differential gene expression
all cells have the same DNA, they just don’t express all their genes at the same time (tissue specific gene expression)
extrons
portions of gene that contribute code for mRNA molecule
introns
don’t contribute info to final mRNA molecule, but regulates gene expression
transcriptional factors
proteins that regulate gene transcription by binding to promoter
activators
activate gene expression
methylation
methyl group added to cytosine DNA by DNA methyltransferase (DNMT); represses gene transcription
why methylation represses gene expression
prevents transcription factors from binding (attracts repressors)
methylation & frog study
when implanted, egg had proteins to remove methyl group and make the gene active again
mitotic lineage
sequence of cell divisions in mitotic cells during ontogeny that gives rise to a particular cell in the individual
asymmetric cell division
daughter cells looks different than mother cell
cell fate
depends on lineage
mosaic specification of fate
cells follow a particular fate no matter what the neighboring cell is doing
study with worms (question)
wanted to see if P1 was dependent on AB
study with worms (test/results)
separate AB and P1, P1 gives rise to cells (not entire organism, eventually collapsed) > follow own fate
SKN 1
posterior of egg, important for setting up pharynx in P1; w/o SKN-1 the cells fated to produce the pharynx will just form extra skin
what happens if cells die during development? (worms)
laser ablation, killed cell did not come back (cells programmed to die still die)
