p53蛋白被称为“基因组守护者”是为什么？
Why is p53 called the 'guardian of the genome'?
p53在DNA受损时被激活，可暂停细胞周期让DNA修复，或启动凋亡清除无法修复的细胞，从而抑制肿瘤发生。其基因突变常见于多种癌症。
When DNA is damaged, p53 halts the cycle for repair or triggers apoptosis to remove irreparable cells, suppressing tumors. Mutations in p53 are common across many cancers.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Alberts 等,《Molecular Biology of the Cell》第6版,Garland Science,2014
B. Alberts et al., Molecular Biology of the Cell, 6th ed., Garland Science, 2014
#p53 #肿瘤抑制 #DNA修复
细胞周期的检查点如何防止出错？
How do cell-cycle checkpoints prevent errors?
检查点由CDK与周期蛋白驱动，在G1/S、G2/M等节点核查DNA是否完整、复制是否完成，不合格就令细胞停滞或进入凋亡，避免把错误传给子细胞。
Checkpoints, driven by CDKs and cyclins, verify DNA integrity and replication completion at points like G1/S and G2/M; if flawed, the cell stalls or dies rather than passing errors to daughters.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Alberts 等,《Molecular Biology of the Cell》第6版,Garland Science,2014
B. Alberts et al., Molecular Biology of the Cell, 6th ed., Garland Science, 2014
#检查点 #CDK #周期蛋白
只要还有一条染色体未与纺锤体正确连接,细胞就宁肯全面停摆也不进入后期——请描述把“动粒未连接”翻译成“APC/C沉默”的那套监控回路。
When even one chromosome lacks proper spindle attachment, the cell halts outright rather than enter anaphase—describe the surveillance circuit that converts unattached kinetochores into APC/C silencing.
未连接的动粒上组装出含Mad2、Mad3(BubR1)、Bub3与Cdc20的检查点复合物,Mad2如安全带锁扣般钳住Cdc20使其失活。失去自由Cdc20,后期促进复合物APC/C便无法泛素化securin,分离酶持续被抑,姐妹染色单体间的黏连蛋白得以保全。直到最后一个动粒完成两极连接,检查点信号熄灭,Cdc20获释,细胞才同步踏入后期。
Unattached kinetochores assemble a checkpoint complex containing Mad2, Mad3 (BubR1), Bub3, and Cdc20; Mad2 clamps onto Cdc20 like a seat-belt buckle and holds it inactive. With no free Cdc20, the APC/C cannot ubiquitinate securin, separase remains inhibited, and cohesin holding sister chromatids together stays intact. Only when the final kinetochore achieves bipolar attachment does checkpoint signaling lapse, Cdc20 is released, and the cell commits to anaphase in unison.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Musacchio 与 Salmon 的检查点机制权威综述,《Nature Reviews Molecular Cell Biology》2007年第8卷第369–381页。
Musacchio A & Salmon ED, The spindle-assembly checkpoint in space and time, Nature Reviews Molecular Cell Biology 8: 369–381 (2007).
独立核验依据 · Independent verification: 核验依据 1 EUROPEPMC 标识 17426725：The spindle-assembly checkpoint in
#细胞周期 #纺锤体组装检查点
细胞为什么不把染色体末端的端粒当作待修复的DNA双链断裂,shelterin复合体是如何封住末端的?
Why does a cell not mistake chromosome-end telomeres for repairable DNA double-strand breaks, and how does the shelterin complex cap them?
因为端粒上的shelterin复合体把染色体末端伪装成受保护染色质。TRF1与TRF2结合双链TTAGGG重复,POT1覆盖富G的单链3′突出端,再由TPP1、TIN2和RAP1交联成六亚基装置;TRF2抑制ATM信号并推动t环把突出端藏入双链区,POT1阻断ATR招募,二者还遏制非同源末端连接以防端粒互融。TRF2或POT1一旦缺失,裸露末端即刻触发p53依赖的损伤应答与染色体桥接。
Because the shelterin complex assembled on telomeric repeats disguises the terminus as protected chromatin. TRF1 and TRF2 bind duplex TTAGGG repeats, POT1 caps the G-rich single-stranded 3-prime overhang, and TPP1, TIN2 and RAP1 cross-link them into a six-subunit apparatus. TRF2 suppresses ATM signaling and drives t-loops that tuck the overhang into duplex DNA, while POT1 blocks ATR recruitment; both also restrain non-homologous end joining so telomeres cannot fuse. Lose TRF2 or POT1 and the naked end instantly triggers a p53-dependent damage response and chromosome bridging.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Denchi EL与de Lange T论文《Protection of telomeres through independent control of ATM and ATR by TRF2 and POT1》,Nature 2007(洛克菲勒大学de Lange实验室)
Denchi EL & de Lange T, 'Protection of telomeres through independent control of ATM and ATR by TRF2 and POT1', Nature, 2007 (de Lange lab, Rockefeller University)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1038/nature06065：Protection of telomeres
#端粒 #shelterin #DNA损伤应答
有丝分裂和减数分裂主要区别是什么？
What is the main difference between mitosis and meiosis?
有丝分裂产生两个遗传相同的体细胞，用于生长修复；减数分裂产生四个遗传物质减半的配子，并发生基因重组，是有性生殖的基础。
Mitosis makes two genetically identical somatic cells for growth and repair; meiosis makes four genetically halved gametes with recombination, forming the basis of sexual reproduction.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Alberts 等,《Molecular Biology of the Cell》第6版,Garland Science,2014
B. Alberts et al., Molecular Biology of the Cell, 6th ed., Garland Science, 2014
#有丝分裂 #减数分裂 #配子
细胞周期中 G1/S 和 G2/M 检查点分别监控什么?CDK 与周期蛋白如何驱动这些转换?
What do the G1/S and G2/M checkpoints of the cell cycle each monitor, and how do CDK-cyclin complexes drive these transitions?
G1/S 检查点(限制点)评估营养、生长因子和 DNA 完整性,只有条件合适时 E2F 才解除抑制,R 型 cyclin D/CDK4、6 与 cyclin E/CDK2 磷酸化 Rb,释放 E2F 启动 S 期基因转录。G2/M 检查点确认 DNA 复制完成且损伤已修复,cyclin B/CDK1 经 CAK 激活并被 Wee1/Cdc25 磷酸化开关精细调节,累积到阈值后驱动核膜破裂和染色体凝集。纺锤体组装检查点再通过 Mad2 阻滞 securin 降解,确保姐妹染色单体在全部双极附着前不分离。
The G1/S checkpoint (restriction point) assesses nutrients, growth factors, and DNA integrity; when conditions suffice, cyclin D/CDK4-6 and cyclin E/CDK2 phosphorylate Rb, freeing E2F to transcribe S-phase genes. The G2/M checkpoint verifies complete replication and repaired damage; cyclin B/CDK1 is activated through CAK and fine-tuned by the Wee1/Cdc25 phosphorylation switch, and once past threshold it drives nuclear envelope breakdown and chromosome condensation. The spindle assembly checkpoint then holds securin degradation via Mad2 so sister chromatids separate only after full bipolar attachment.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Alberts 等,《Molecular Biology of the Cell》第6版,Garland Science,2014
B. Alberts et al., Molecular Biology of the Cell, 6th ed., Garland Science, 2014
#细胞周期 #检查点调控
细胞周期分为哪几个阶段？
What are the phases of the cell cycle?
细胞周期包括G1（生长）、S（DNA复制）、G2（准备）和M（有丝分裂）四个阶段，间期（G1/S/G2）占大部分时间。
The cell cycle has G1 (growth), S (DNA replication), G2 (preparation), and M (mitosis). Interphase (G1/S/G2) takes up most of the time.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Alberts 等,《Molecular Biology of the Cell》第6版,Garland Science,2014
B. Alberts et al., Molecular Biology of the Cell, 6th ed., Garland Science, 2014
#细胞周期 #有丝分裂 #分裂
为什么说端粒缩短设定了体细胞的分裂极限,而端粒酶又能让癌细胞突破这一极限?
How does telomere shortening set the division limit of somatic cells, and how does telomerase let cancer cells break through it?
因为线性染色体末端每复制一次就缩短一分。滞后链引物去除后末端无法完全复制,TTAGGG重复序列逐代丢失,短到临界便触发p53介导的衰老与增殖停滞,即Hayflick极限;生殖细胞、干细胞以及约九成癌细胞持续表达端粒酶逆转录酶hTERT,以其自带RNA模板反转录补齐端粒重复序列,从而近乎无限传代,hTERT也因此兼具抗衰老与抗癌双重研究价值。
Because chromosome ends lose material with every replication cycle. Removing lagging-strand primers leaves ends incompletely copied, so TTAGGG repeats erode generation by generation; once shortening crosses a threshold, p53-mediated senescence halts division - the Hayflick limit. Germ cells, stem cells, and roughly ninety percent of cancers keep expressing telomerase reverse transcriptase hTERT, which extends telomeres from its RNA template and permits near-endless doubling, making hTERT both an anti-aging puzzle and an anticancer target.
难度 入门 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Harley CB等论文《Telomeres shorten during ageing of human fibroblasts》,Nature 1990(加拿大麦克马斯特大学,与美国冷泉港实验室合作)
Harley CB et al., 'Telomeres shorten during ageing of human fibroblasts', Nature, 1990 (McMaster University with Cold Spring Harbor Laboratory)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1038/345458a0：Telomeres shorten during ag
#端粒 #端粒酶 #细胞衰老