什么是表观遗传学？
What is epigenetics?
表观遗传学研究在不改变 DNA 序列的前提下，基因表达如何被可逆地调控。常见的机制包括 DNA 甲基化和组蛋白修饰，它们能开启或关闭基因，并可能受环境、饮食和应激影响，部分变化还能在细胞间甚至代际间传递。
Epigenetics studies reversible regulation of gene expression without changes to the DNA sequence. Common mechanisms include DNA methylation and histone modification, which switch genes on or off and can be influenced by environment, diet, and stress; some changes are transmitted between cells and even across generations.
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
#表观遗传 #DNA甲基化 #组蛋白 #基因调控
什么是生物学中的「中心法则」？
What is the central dogma of biology?
中心法则描述了遗传信息在细胞内流动的基本方向：DNA 通过转录生成 RNA，RNA 再通过翻译生成蛋白质。少数病毒中存在逆转录（RNA 到 DNA）等例外，但「DNA→RNA→蛋白质」仍是绝大多数生命形式信息传递的主线。
The central dogma describes the basic flow of genetic information in cells: DNA is transcribed into RNA, and RNA is translated into protein. Exceptions exist in some viruses, such as reverse transcription (RNA to DNA), but DNA to RNA to protein remains the main pathway of information transfer in most life forms.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
《分子生物学》
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）
#中心法则 #转录 #翻译 #遗传信息
为什么每种酶通常只催化一种特定的反应？
Why does each enzyme usually catalyze only one specific reaction?
酶是蛋白质（少数为 RNA），其活性中心具有特定的三维形状与化学环境，只有形状、电荷匹配的底物才能结合，这被称为锁钥学说与诱导契合。这种专一性让细胞内成千上万种化学反应能互不干扰地精确进行。
Enzymes are proteins (or, rarely, RNA) whose active sites have a specific three-dimensional shape and chemical environment, so only substrates with matching shape and charge can bind, described by the lock-and-key and induced-fit models. This specificity lets thousands of reactions proceed precisely without interfering with one another.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Lehninger,《生物化学原理》(Lehninger Principles of Biochemistry)
Lehninger Principles of Biochemistry
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-319-45541-5 (8th ed., Macmillan Learning)
#酶 #专一性 #活性中心 #催化
DNA 复制为什么被称为半保留复制？
Why is DNA replication called semi-conservative?
在 DNA 复制过程中，双链解开后，每条旧链都作为模板合成一条全新的互补链。复制完成的两个子代 DNA 分子中，每个都保留了一条来自亲代的旧链和一条新合成的链，因此称为半保留复制。这一机制由 Meselson 与 Stahl 用同位素实验证实。
During DNA replication the two strands separate, and each parental strand serves as a template for a new complementary strand. Each of the two daughter DNA molecules therefore contains one old strand from the parent and one newly synthesized strand, which is why the process is called semi-conservative. Meselson and Stahl confirmed this with isotope-labeling experiments.
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
#DNA复制 #半保留 #模板 #碱基互补配对
核糖体在细胞中承担什么功能？
What function do ribosomes perform in the cell?
核糖体是由 rRNA 和蛋白质组成的大型复合物，是细胞内进行翻译、把 mRNA 上的遗传密码转译成多肽链的场所。它读取 mRNA 的三联体密码，并将对应的氨基酸按顺序连接成蛋白质，是几乎所有生命体都必需的核心机器。
Ribosomes are large complexes of rRNA and protein that carry out translation, reading the genetic code on mRNA and assembling amino acids into polypeptide chains. By decoding mRNA codons in order, they produce proteins and are essential molecular machines in virtually all living organisms.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
《分子生物学》
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）
#核糖体 #翻译 #rRNA #蛋白质合成
PCR（聚合酶链式反应）是用来做什么的？
What is PCR (polymerase chain reaction) used for?
PCR 是一种在体外快速扩增特定 DNA 片段的技术。它通过反复加热使 DNA 变性、降温使引物退火、再在中温下由耐热 DNA 聚合酶延伸，每个循环使目标片段数量翻倍，从而在几小时内获得数百万份拷贝，常用于检测、诊断和法医鉴定。
PCR is a technique for rapidly amplifying a specific DNA fragment in vitro. It repeatedly cycles through heating to denature DNA, cooling so primers can anneal, and a middle temperature where a heat-stable DNA polymerase extends the strands. Each cycle doubles the target, yielding millions of copies within hours, and it is widely used in testing, diagnosis, and forensics.
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
#PCR #聚合酶链式反应 #DNA扩增 #引物
DNA 是由什么组成的？
What is DNA made of?
DNA（脱氧核糖核酸）由四种脱氧核糖核苷酸组成，每种核苷酸含有一个磷酸基团、一个脱氧核糖和一个含氮碱基（腺嘌呤、胸腺嘧啶、鸟嘌呤或胞嘧啶）。这些核苷酸通过磷酸二酯键连接成两条反向平行的长链，再盘绕成双螺旋结构。
DNA (deoxyribonucleic acid) is built from four kinds of deoxyribonucleotides, each containing a phosphate group, a deoxyribose sugar, and one nitrogenous base (adenine, thymine, guanine, or cytosine). The nucleotides are linked by phosphodiester bonds into two antiparallel strands that coil into a double helix.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
《分子生物学》
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 #脱氧核糖核酸 #核苷酸 #双螺旋 #碱基
蛋白质是用什么做成的小积木搭起来的？
What little building blocks are proteins made from?
蛋白质是由许多叫做氨基酸的小分子像串珠子一样连起来组成的。人体需要二十种不同的氨基酸，它们按不同顺序组合，就能变成肌肉、头发、消化食物的酶等各种各样的蛋白质。
Proteins are made by linking many small molecules called amino acids together, like beads on a string. The human body uses about twenty kinds of amino acids, and by arranging them in different orders it builds many different proteins such as muscle, hair, and the enzymes that digest food.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
《生物化学》
Lehninger Principles of Biochemistry
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-319-45541-5 (8th ed., Macmillan Learning)
#蛋白质 #氨基酸 #酶 #营养素