Week 7

essential for signaling cells to divide and grow (proliferate) • mutated in 30% of human cancers

stimulates cell growth and division even when there is no external EGF binding to EGF-R (However, microRNA Let-7 can block mutant RAS)

no translation by ribosome –> no RAS protein

by blocking translation

external signal lig (bind) as in “ligature”

external signal (ligand) membrane receptor internal signal transduction internal response

hormones… gland secretion into blood

chem signal secreted from neighbour cells

chem signal secreted and acting on source cell

all-trans retinoic acid • derived from vitamin A • binds receptors and activates genes needed for differentiation

i.e. testosterone promote growth and cell division in some tissues

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

process by which certain living cells called phagocytes ingest or engulf other cells or particles

mitochondria into cytoplasm during apoptosis • stops ATP synthesis, stopping cell metabolism

attached to inner membrane It transfers electrons to molecules (respiratory complexes) so they can move protons needed for ATP synthesis.

pro-apoptosis gene / “tumour suppressor” proteins causes opening of outer membrane when activated

proteins activated when cytochrome c is released

degrading cytoplasm contents include protein fragments

decays in lungs radioactive polonium metal is deposited. • Radioactive polonium and other metallic decay products remain in lungs emitting alpha or beta particles until non-radioactive lead is produced.

healthy and fit 31-year-old non-smoker diagnosed with metastatic lung cancer (p. 37, Sidebar 2.3), and died at 33. • believed radon in family home cause

production in larger amounts may keep cancer cells from dying (survival signals)

unregulated ability to grow and divide no/only partial differentiation • mitogens : abundant, overactive, unregulated • antimitogens : suppressed increased mutation rate

activating, dominant, gain of function mutations, increased expression, affecting Bcl2 for example

chemical signalling (internally and externally)