Week 7 Flashcards
RAS proteins
essential for signaling cells to
divide and grow (proliferate)
- mutated in 30% of human cancers
Mutant Ras protein
stimulates cell growth
and division even when there is no external
EGF binding to EGF-R
(However, microRNA Let-7 can block mutant
RAS)
when RAS RNA binds let-7
no translation by ribosome –> no RAS protein
how do microRNAs control gene expression
by blocking translation
ligand
external signal
lig (bind) as in “ligature”
simple chemical signalling model
external signal (ligand)
membrane receptor
internal signal transduction
internal response
Endocrine signalling
hormones…
gland secretion into blood
Paracrine signalling
chem signal secreted from neighbour cells
Autocrine signalling
chem signal secreted and acting on source cell
ATRA
all-trans retinoic acid
- derived from vitamin A
- binds receptors and activates genes needed for differentiation
steroid hormones
i.e. testosterone
promote growth and cell
division in some tissues
what gene mutations and mutation effects would benefit tumour development
dominant mutations
gain-of-function mutations
mutation that results in an overactive mitogen’
mutation that results in unregulated mitogen
mutation results in excessive mitogen synthesis
phagocytosis
process by which certain living cells called phagocytes ingest or engulf other cells or particles
cytochrome c released from cell
mitochondria into cytoplasm during apoptosis
- stops ATP synthesis, stopping cell metabolism
cytochrome c purpose in normal cell
attached to inner membrane
It transfers electrons to molecules
(respiratory complexes) so they can
move protons needed for ATP
synthesis.
