CELL DEATH AND RENEWAL Flashcards
when is apoptosis beneficial to an organism?
orchestrated cell death allows for replacement of old cells, ensures damaged cells won’t multiply, and helps immune system
what is proliferation and do all adult cells perform it?
cell reproduction/growth; most cells are non-proliferating (we don’t need all cells constantly growing!)
what is the G0 phase and what role does it play?
‘resting phase’ of cell cycle; cell enters to pause growth and may exit to re-enter proliferation
what role do PDGFs and FGFs play in proliferation?
PDGFs - growth factors for fibroblasts; activate fibroblasts upon injury to allow for proliferation
FGFs - fibroblast growth factors; have positive and negative regulation of proliferation
what are two traits of stem cells?
1.) self-renewing; one daughter cell differentiates and one remains stem cell
2.) proliferate quickly; can rapidly produce differentiated cells
what are transient amplifying cells?
pluripotent and highly proliferative; undifferentiated and fast dividers
what is bone marrow transplantation?
an infusion of healthy blood-forming stem cells into your body to replace bone marrow that’s producing unhealthy cells; advantages include improved cellularity but a disadvantage is that adult stem cells are hard to isolate
how can we use mammalian embryonic stem cells?
pluripotent cells that can be used to differentiate and obtain specific cell types; easy to use for testing but do have ethical concerns
what is somatic nuclear transfer?
removal of nucleus from egg and replacing it with a somatic cell’s nucleus - this will create a cloned offspring
pros are no rejection risks b/c cells come from patient
cons are ethical concerns and low efficiency
what are induced pluripotent stem cells?
can turn back the clock and reprogram adult stem cells = no embryos required; used for disease modeling
why might it be better to use induced pluripotent stem cells over mammalian or somatic?
induced stem cells may be best to use because they have unlimited ability to self-renew and create various differentiated cells; form autoregulatory loop
what is the role of the core transcriptional program found in stem cells?
composed of oct4, sox2, and nanog; form autoregulatory loop that acts on other genes to maintain stem cell state - regulation of gene expression, cell identity, and differentiation
what is transdifferentiation?
process of differentiating an adult somatic cell into another differentiated cell
what are the characteristics of apoptotic cells?
programmed cell death that balances cell proliferation; apoptotic cells have fragmented dna and no nucleus
in what key aspect does cell death by apoptosis differ from necrosis?
apoptosis is programmed where necrosis is uncontrolled; apoptotic cells break into smaller bodies, necrotic cells lyse/rupture
how do phagocytic cells differentiate between normal and apoptotic cells?
the phosphatidylserine from the inner membrane flips to the outer, serving as an ‘eat me’ signal
what are key targets of effector caspases?
cleaved cytoskeleton, nuclear lamina, and dna repair enzymes
how are initiator caspases different from effector caspases?
initiators are activated directly in response to apoptosis signals where effectors are activated by initiators and digest necessary proteins for apoptosis
how does activation of Bax/Bak lead to apoptosis?
proapoptotic effector proteins; activated by BH3-only proteins and inhibited by Bcl-2; excess p53 will activate bax, create permeable mitochondrial membrane, release cytochrome C, and activates caspase-9 (apoptosis regulator)
