🎲 基因突变：说明书抄错一个字🎲 Gene Mutation: one typo in the manual
上一片说，每个孩子从父母各拿一张基因卡。可这本"生命说明书"有几十亿个字母，抄写的时候写错了怎么办？Last leaf, every child drew a gene card from each parent. But the instruction manual is billions of letters long — what happens when copying slips up?
第 1 步：说明书里的错字Step 1: A typo in the manual
先翻开小细胞的说明书看看。First, open the little cell's manual.
DNA 是一串字母写成的大书，字母只有四种：A、T、G、C。抄写员（复制酶）抄错一个字母，就是一次基因突变。就像把"猫"写成"猪"，一句话的意思可能完全变样。DNA is a giant book written in just four letters: A, T, G, C. When the copyist enzyme gets one letter wrong, that's a gene mutation — like typing "eat" instead of "tea". One letter, and the meaning can flip.
一个字母的错，能错出几种花样？One letter — how many ways can it go wrong?
替换：一个字母换成另一个，只错一处；缺失：丢掉一个字母；增添：多插进一个字母。替换像改一个字，后面的句子还能读；缺失和增添却会让后面全部"串位"——从错点开始的整句话都读歪了。Substitution swaps one letter — a single spot changes. Deletion drops a letter; insertion squeezes one in. A substitution edits one word and the rest still reads; deletions and insertions shift every letter after the mistake, garbling the whole tail of the sentence.
那突变会不会生出怪兽？So does a mutation make a monster?
第 3 步：错字不一定是灾难Step 3: Not every typo is a disaster
大多数错字落在不影响意思的地方，什么也不改变；少数改坏了关键句子，可能致病；偶尔改出新本事，比如让植物更耐旱。辐射、化学物质和复制错误都能引发突变。突变没有"想要"的方向，好坏由环境来打分——它是进化的原料，不是怪兽制造机。Most typos land where they change nothing; a few break a vital sentence and may cause disease; now and then one invents a new trick, like a crop that shrugs off drought. Radiation, chemicals and copying errors can all trigger them. Mutations have no intention — the environment grades them. They are evolution's raw material, not a monster maker.
🎮 你来当检错员（30 秒）🎮 Your turn: proofread (30 seconds)
道理讲完了。对照两行字母，点出错位、选出错法，找出 4 关里的抄写错误。Theory done. Compare the two letter rows, tap the wrong spot, pick the mistake type, and catch the typos in all 4 levels.
一句话记住它：突变 = 生命说明书里的错字；多数无害、少数致病、偶有有利——随机发生，是进化的原料。Remember it in one line: a mutation is a typo in life's manual — mostly harmless, rarely harmful, occasionally helpful; random, and the raw material of evolution.
突变 = DNA 序列的改变：替换、缺失、增添（后两种会让后面串位）A mutation is a change in the DNA sequence: substitution, deletion, insertion (the last two shift everything after)诱因：辐射、化学物质、复制出错；突变随机发生，没有方向Causes: radiation, chemicals, copying errors; mutations happen at random, with no direction多数无害、少数致病、偶有有利；突变 ≠ 怪兽Mostly harmless, rarely harmful, occasionally helpful; mutation ≠ monster
内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.
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