测序仪是怎样“读出”DNA序列的？
How does a sequencer 'read' a DNA sequence?
现代测序把DNA打断、加接头并扩增成簇，逐一记录每个循环掺入的碱基荧光，再经算法拼回完整序列，可同时处理数十亿片段。
Modern sequencers fragment DNA, add adapters, and amplify clusters, recording the fluorescence of each base added per cycle, then assembling the full sequence by algorithm across billions of fragments.
难度 专业 · 适合 大众
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
#测序原理 #荧光 #拼装
端粒为何会随着细胞分裂逐渐缩短，端粒酶如何抵消这一过程？
Why do telomeres shorten with each cell division, and how does telomerase counteract this?
DNA 聚合酶无法完全复制线性染色体末端（末端复制问题），导致端粒每次分裂丢失 50–200 个碱基；端粒酶以自身 RNA 为模板用逆转录延长端粒，在生殖细胞、干细胞和多数癌细胞中活跃，从而维持染色体稳定。
The end-replication problem prevents DNA polymerase from copying chromosome ends fully, losing 50–200 bp per division; telomerase uses its intrinsic RNA template to extend telomeres by reverse transcription, staying active in germ cells, stem cells and most cancers to preserve genome stability.
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
#端粒 #端粒酶 #衰老
错配修复系统如何识别哪条链是需要修正的新合成链？
How does mismatch repair recognize which strand is the newly synthesized one to correct?
在原核生物中，错配修复蛋白 MutS 识别错配，MutL 与 MutH 协作，由 Dam 甲基化标记区分模板链（已甲基化）与新链（暂未甲基化），从而只切除并修正新链上的错误。
In prokaryotes, MutS recognizes mismatches and MutL/MutH act together; strand discrimination relies on Dam methylation marking the parental template as methylated while the nascent strand is briefly unmethylated, so only the new strand is excised and corrected.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
Annual Review of Biochemistry
Annual Review of Biochemistry
#错配修复 #甲基化 #保真度
实时定量PCR（qPCR）如何测出样品里有多少模板？
How does quantitative real-time PCR (qPCR) measure template amount?
qPCR在扩增时实时检测荧光，模板越多、达到设定阈值的循环数（Ct值）越早，据此可定量起始DNA或RNA的量。
qPCR monitors fluorescence during amplification; more starting template reaches the threshold cycle (Ct) earlier, letting it quantify the initial DNA or RNA amount.
难度 专业 · 适合 大众
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
#qPCR #Ct值 #定量
可变剪接如何使一个基因产生多种蛋白质？
How does alternative splicing allow one gene to produce multiple proteins?
前体 mRNA 中的外显子可通过不同组合被保留或切除，一个基因由此产生多种成熟 mRNA 异构体，翻译出结构和功能不同的蛋白质；这是人类蛋白质组复杂度高于基因数量的主要原因。
Exons of a pre-mRNA can be included or skipped in different combinations, yielding multiple mature mRNA isoforms from one gene that translate into proteins with distinct structures and functions—a major reason human proteome complexity exceeds gene count.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Lewin's Genes XII,Jones & Bartlett Learning,2018
Lewin's Genes XII, Jones & Bartlett Learning, 2018
#剪接 #外显子 #蛋白质组
DNA 聚合酶合成新链时为什么只能沿 5'→3' 方向进行？
Why can DNA polymerase only synthesize new strands in the 5'→3' direction?
DNA 聚合酶只能在已有引物的 3' 羟基末端添加核苷酸，因为形成磷酸二酯键的能量来自进入核苷酸的 5' 三磷酸基团，因此新链只能从 5' 向 3' 延伸，使后随链以冈崎片段方式不连续合成。
DNA polymerases add nucleotides only to the 3'-OH end of a primer because bond formation is powered by the incoming nucleotide's 5' triphosphate, so synthesis proceeds 5'→3' and the lagging strand is made discontinuously as Okazaki fragments.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
《分子生物学》教材
Molecular Biology of the Cell (Alberts)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787030261946（豆瓣书目条目: 分子生物学）
#DNA复制 #聚合酶
一代（桑格）测序和二代测序有什么不同？
How does Sanger (first-gen) sequencing differ from next-generation sequencing?
桑格测序一次读一条较长片段、准确但通量低；二代测序可并行读出海量短片段，速度快成本低，适合全基因组与宏基因组。
Sanger reads one long fragment at a time—accurate but low throughput; next-gen sequencing reads massive numbers of short fragments in parallel, fast and cheap for whole genomes.
难度 进阶 · 适合 大众
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
#测序 #桑格 #二代
逆转录酶的存在是否违背了中心法则？
Does the existence of reverse transcriptase violate the central dogma?
中心法则描述的是遗传信息流的普遍方向，而逆转录酶以 RNA 为模板合成 DNA，是信息流的一种特例，常见于逆转录病毒和端粒酶；它拓展了而非推翻中心法则。
The central dogma describes the general direction of genetic information flow; reverse transcriptase synthesizes DNA from an RNA template, a documented exception seen in retroviruses and telomerases, which extends rather than overturns the dogma.
难度 进阶 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Lewin's Genes XII,Jones & Bartlett Learning,2018
Lewin's Genes XII, Jones & Bartlett Learning, 2018
#逆转录 #中心法则 #病毒
原核生物的转录和翻译为何可以偶联，而真核生物不能？
Why can transcription and translation be coupled in prokaryotes but not in eukaryotes?
原核生物没有核膜，核糖体可在 mRNA 尚未转录完成时便结合其 5' 端开始翻译；真核生物转录在细胞核内进行，而翻译在细胞质中，且 mRNA 需经过加帽、剪接和加尾等加工后才能出核。
Prokaryotes lack a nuclear membrane, so ribosomes can bind the 5' end of an mRNA and start translating while transcription is still underway; in eukaryotes transcription occurs in the nucleus and translation in the cytoplasm, with mRNA processing (capping, splicing, polyadenylation) required before export.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Lewin's Genes XII,Jones & Bartlett Learning,2018
Lewin's Genes XII, Jones & Bartlett Learning, 2018
#转录 #翻译 #原核生物
遗传密码的简并性是什么意思？
What does degeneracy of the genetic code mean?
大多数氨基酸由多个密码子编码，这种现象称为简并性；它使 DNA 突变有时不改变所编码的氨基酸，从而降低了有害突变的概率。
Most amino acids are encoded by more than one codon, a property called degeneracy; it means some DNA mutations do not change the encoded amino acid, buffering the impact of harmful mutations.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Lewin's Genes XII,Jones & Bartlett Learning,2018
Lewin's Genes XII, Jones & Bartlett Learning, 2018
#密码子 #简并性 #突变
PCR是怎样把DNA放大许多倍的？
How does PCR amplify DNA many times over?
PCR用高温变性、降温让引物结合、中温让DNA聚合酶延伸的循环，每一轮使目标DNA翻倍，几十轮后可获数百万倍拷贝。
PCR cycles through heating to separate strands, cooling so primers bind, and warming for polymerase extension; each cycle doubles the target, yielding millions of copies in dozens of rounds.
难度 入门 · 适合 大众
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
#PCR #扩增 #引物