G1/S/G2/M phases, cyclins, CDKs, mitosis, cytokinesis, meiosis, spindle-assembly checkpoint.
Cell Cycle
Cell cycle
Ordered sequence of events duplicating and partitioning the cell: G1 → S (DNA replication) → G2 → M (mitosis + cytokinesis). Checkpoints…
Cyclin
Regulatory subunit whose cyclic synthesis + degradation paces the cell cycle. Cyclin D (G1), E (G1/S), A (S/G2), B (M). Bind and activate…
Cyclin-dependent kinase (CDK)
Ser/Thr kinase active only when bound to cognate cyclin + T-loop phosphorylated + CKI-unbound. CDK1 (MPF, mitosis), CDK2 (S-phase), CDK4/6…
Mitosis
Chromosome partitioning via microtubule-based spindle: prophase → prometaphase → metaphase (bi-orientation) → anaphase (sister-chromatid…
Meiosis
Specialised division producing 4 haploid gametes from one diploid cell via two successive divisions. MI: homologous pairing + crossing over…
Spindle assembly checkpoint (SAC)
Surveillance mechanism delaying anaphase until every kinetochore is bi-oriented. Unattached kinetochores produce MCC (Mad2, BubR1, Bub3)…
p53 tumor suppressor
'Guardian of the genome': transcription factor activated by DNA damage, hypoxia, oncogene stress. Induces cell-cycle arrest (p21),…
G1/S transition (Rb/E2F)
CycD-CDK4/6 phosphorylates Rb, releases E2F, drives S-phase genes. Restriction point: commit to division. Rb loss (retinoblastoma) bypasses…
DNA damage checkpoint (ATM/ATR)
DSBs activate ATM → Chk2 → p53; stalled forks activate ATR → Chk1. Halt cycle, recruit repair, or apoptose. Tumor-suppressor network.
Anaphase-promoting complex (APC/C)
E3 ubiquitin ligase that polyubiquitinates securin and cyclin B, triggering sister-chromatid separation and mitotic exit. Cdc20 + Cdh1…
CDK bistable switch (Tyson-Novak)
Cyclin-CDK regulatory network exhibits hysteretic bistability via positive feedback (Cdc25 activation, Wee1 inactivation) generating…
Chromosome segregation error kinetics
Mitotic error rate epsilon ~ 10^-5 per chromosome reflects Markovian kinetochore-microtubule attachment dynamics: amphitelic (correct) vs…
Cyclin-CDK engine (Hartwell-Hunt-Nurse)
Hartwell + Hunt + Nurse Nobel 2001: cyclins synthesized + degraded periodically activate CDK kinases; G1/S/G2/M-cyclins drive progression;…
G1/S checkpoint (Rb-E2F)
Knudson 1971 + Weinberg 1990s Rb tumor-suppressor: hypophosphorylated Rb binds E2F; cyclinD-CDK4/6 phosphorylates Rb -> E2F released ->…
DNA damage checkpoint (ATM/ATR)
Lavin 1980s ATM + Cimprich-Cortez 2008 ATR: PIKK family kinases sense DSB (ATM-MRN) + ssDNA (ATR-RPA); phosphorylate Chk1/2 -> Cdc25…
Spindle assembly checkpoint (Mad/Bub)
Murray-Kirschner 1991 + Hoyt 1991 MAD/BUB checkpoint: unattached kinetochores generate MCC complex inhibiting APC/C-Cdc20 ->…
Microtubule dynamic instability (Mitchison-Kirschner 1984)
Mitchison-Kirschner 1984: MT alpha-beta tubulin dimers polymerize at + end; GTP-cap stabilizes; catastrophe / rescue transitions; basis of…
Cytokinesis (actomyosin ring)
Schroeder 1972 + Glotzer 2005 contractile-ring: RhoA-GTPase -> formin-mediated actin assembly + myosin-II ATPase contraction; cleavage…
G0 quiescence (Coller 2006)
Coller 2006 + Sang-Massague 2010 G0-quiescence regulation; modern stem-cell-niche + cancer-dormancy.
Cell-cycle arrest (Malumbres 2009)
M Malumbres-M Barbacid 2009 'Cell cycle CDKs and cancer' Nat Rev Cancer; modern CDK4/6 inhibitors palbociclib 2015 + 2024.
APC/C (King 1995)
R King-J Peters 1995 anaphase-promoting-complex/cyclosome; modern Cdc20 vs Cdh1 specifier; cell-cycle-exit timing.
p21 (el-Deiry 1993)
el-Deiry 1993 + Harper 1993 p21-WAF1/CIP1 + p27-Kip1 CDK-inhibitors; modern senescence + cancer-therapy targets.
Contact inhibition (Stoker 1973)
M Stoker 1973 contact-inhibition; modern Hippo-YAP-TAZ pathway Pan 2010 + cancer-loss + organ-size.
Centrosome cycle (Fukasawa 1996)
K Fukasawa 1996 centrosome-cycle; modern Plk4-orchestrated centriole-duplication; cancer + ciliopathy implications.