端粒和端粒酶有什么作用？
What do telomeres and telomerase do?
端粒是染色体末端的重复序列“保护帽”，每次复制会变短；端粒酶能重建端粒，干细胞和多数癌细胞借此维持长度、延长寿命。
Telomeres are protective repeat 'caps' at chromosome ends that shorten with each replication; telomerase rebuilds them, letting stem cells and most cancer cells stay long-lived.
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
#端粒 #端粒酶 #衰老
DNA聚合酶为什么需要引物？冈崎片段是什么？
Why does DNA polymerase need a primer, and what are Okazaki fragments?
DNA聚合酶只能从已有核苷酸的3′端延伸，需RNA引物起始；后随链不连续合成，形成许多短的冈崎片段，再被连接酶连成完整链。
DNA polymerase can only extend from an existing 3′ end, so an RNA primer is needed to start; the lagging strand is made in short Okazaki fragments that are later joined by ligase.
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
#引物 #冈崎片段 #后随链
DNA复制为什么叫“半保留”？
Why is DNA replication called 'semi-conservative'?
复制时双链解开，每条旧链作为模板合成一条新链，因此每个子代DNA分子都含一条旧链和一条新链，各保留一半亲代信息。
The two strands separate, each serving as a template for a new strand, so every daughter DNA molecule keeps one old and one new strand—conserving half the parental information.
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
#半保留 #复制 #双螺旋