GMS 6540 exam with complete answers

Ras signaling - GTPase - promotes growth and proliferation - mutated in 20-30% of all cancers - point mutations are most common G12V mutation - blocks GAP binding - locks RAS in active state, promoting proliferation Q61K mutation - raises activation energy of GTP hydrolysis - blocking hydrolysis, keeping RAS active Hallmarks of cancer 1) self-sufficiency in growth signals 2) insensitivity to anti-growth signals 3) unstable DNA 4) metastasis 5) evasion of apoptosis 6) abnormal cellular metabolism 7) angiogenesis 8) inflammation 9) evasion of immune system 10) immortality Anti-growth signals - can be internal or external - can be normal or induced - must be overcame in normal cells to proliferate p53 - damage sensor - tumor suppressor gene - halts cell cycle at G1 phase - 50% of tumors contain mutation or deletion R72P mutation - block DNA binding Rb - binds E2F (transcription factor) blocking transcription - when phosphorylated it releases E2F allowing transcription Rb mutations - mutated, present but unable to bind E2F - downregulated, allows for further transcription - CDK overactivity - allows for Rb to be phosphorylated Unstable DNA - genetic instability - chromosomal instability - enabling hallmark - can cause drug resistance Chromosomal instability - gain or loss of whole chromosomes - can get double or quadruple genomes - gain of pro-growth/invasive genes - loss of growth inhibitory genes Endoreduplication - replication without nuclear division - failed cytokinesis Multipolar spindles - monopolar spindle - lagging chromosomes Metastasis - cancer cells move int