Transcript PPoint Lec 18

Cells are regularly destroyed purposefully during
development, and this is a much different process
from cells that die due to damage.
Apoptosis-derived from greek referring to dropping of leaves
in the autumn>morphology of cells degrading in a noninflammatory (not
involving the immune system) manner
>protein synthesis not required
>lysosomes not involved
Programmed Cell Death-cell death that happens as part of a
developmental program
>protein synthesis required
>lysosomes are involved
Terms used interchangeably but technically not the same
thing-the correct term that encompasses both is physiological
cell death (non-trauma, non inflammatory)
23.45,1045
programmed
cell death
highly
stereotypedcan kill off
cells without
killing
surrounding
cells—
cells that die
by necrosis
typically swell
and burst and
may damage
other cells
23.46, 1046 Cells need to constantly receive signal from
neurotrophins (or neutrophins)-protein growth factors that bind
to receptor tyrosine kinases (remember them?) called TRKs.
23.47, 1047
Knockout mice experiments established that specific
neurotrophins are required to maintain populations of certain
neurons.
Caenorhabditis elegans-a flatworm with a
short life cycle and eutely (defined number
of cells-1090 in this case, 131 of which
undergo programmed cell death)
Also-now whole genome is sequenced
Because the fate of each cell can
be traced, mutant strains of worms
have been identified where those
131 cells don’t die. The genes
responsible for this have been
identified and are called
CED genes.
23-48,1047
Models are being built as to the exact mechanism of
programmed cell death.
23-50, 1049
23-50, 1049
View animation
Group Exercise #18