Gene mutations · 基因突变
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| mutation/mjuːˈteɪʃn/ | 突变 | tū biàn |
| base sequence/beɪs ˈsiːkwəns/ | 碱基序列 | jiǎn jī xù liè |
| substitution/ˌsʌbstɪˈtjuːʃn/ | 替换 | tì huàn |
| deletion/dɪˈliːʃn/ | 缺失 | quē shī |
| insertion/ɪnˈsɜːʃn/ | 插入 | chā rù |
| frameshift/ˈfreɪmʃɪft/ | 移码 | yí mǎ |
| reading frame/ˈriːdɪŋ freɪm/ | 阅读框 | yuè dú kuāng |
| silent mutation/ˈsaɪlənt mjuːˈteɪʃn/ | 沉默突变 | chén mò tū biàn |
| natural selection/ˈnætʃərəl sɪˈlekʃn/ | 自然选择 | zì rán xuǎn zé |
When the code goes wrong
- A gene mutation 突变 is a change in the base sequence 碱基序列 of DNA.
- A change in the code can change the polypeptide that is made.
- How much it changes depends on the type of mutation.
当密码出错时
- 一个基因 突变(mutation) 是 DNA 碱基序列 的一个改变。
- 密码的一个改变能改变所制造的多肽。
- 它改变 多少 取决于突变的 类型。
Mutation type lab · 突变类型实验
Compare substitution, insertion and deletion using their effect on the code. · 比较替换、插入和缺失对⟦code⟧的影响。
A gene mutation is: · 基因突变是：
A gene mutation is a change to the sequence of bases in a DNA molecule. · 基因突变是DNA分子中碱基序列的改变。
Substitution 替换
- A substitution swaps one base for a different base.
- It changes at most one amino acid — and sometimes none at all, because the code is degenerate (the new triplet may still code for the same amino acid).
Substitution, deletion 缺失 and insertion 插入 mutations
替换
- 一个 替换(substitution) 把一个碱基换成一个不同的碱基。
- 它 最多 改变 一个 氨基酸——有时 一个也不,因为密码是简并的(新三联体可能仍编码相同的氨基酸)。
替换、缺失和插入突变
A substitution mutation changes: · 替换突变改变了：
Only one triplet is altered, so at most one amino acid changes — and the degenerate code means sometimes none does. · 仅改变一个三联体，因此最多改变一个氨基酸——由于简并性，有时也不变。
A substitution can sometimes leave the amino acid unchanged. · 替换有时不会改变氨基酸。
Because the code is degenerate, the new triplet may still code for the same amino acid — no change. · 因为遗传密码具有简并性，新的三联体可能仍编码相同的氨基酸——即无变化。
Deletion and insertion: frameshift 移码
- A deletion removes a base; an insertion adds an extra base.
- Either one shifts the reading frame 阅读框 — every later triplet is read wrongly.
- So these usually change many amino acids after that point, with a large effect.
缺失和插入:移码
- 一个 缺失(deletion) 移除一个碱基;一个 插入(insertion) 添加一个额外的碱基。
- 任何一个都 移动阅读框——后面每个三联体都被错误地读取。
- 所以这些通常改变那一点之后的 许多 氨基酸,有很大的影响。
original: CAT-GGA-TCC-ATG
substitution: CAT-GCA-TCC-ATG 一个密码子改变
deletion: CAT-GAT-CCA-TG? 阅读框移动 → 所有后面的密码子都改变
Why do deletions and insertions usually have a large effect? · 为什么缺失和插入通常影响巨大？
Adding or removing a base shifts the reading frame, changing all the triplets that follow (a frameshift). · 添加或删除一个碱基会改变阅读框，改变其后所有的三联体（移码）。
Adding or removing a base shifts the reading frame — this is called a ______ mutation. · 添加或删除一个碱基会改变阅读框——这被称为______突变。
Every triplet after the change is read wrongly, so the protein is usually badly affected. · 改变后的每个三联体都被错误读取，因此蛋白质通常受到严重影响。
Match each mutation to its effect. · 将每种突变与其效应匹配。
Substitutions affect at most one amino acid; insertions and deletions cause a frameshift; a silent mutation changes nothing. · 替换最多影响一个氨基酸；插入和缺失引起移码；沉默突变不改变任何内容。
Not every mutation matters
- The genetic code is degenerate, so some base changes still code for the same amino acid — a silent mutation 沉默突变.
- Most mutations are harmful or neutral, but a rare beneficial one is the raw material for natural selection 自然选择.
不是每个突变都重要
- 遗传密码是 简并的,所以一些碱基改变仍编码相同的氨基酸——一个 沉默(silent) 突变。
- 大多数突变是有害的或中性的,但一个罕见的有益突变是 自然选择的原材料。
You've got it
- a mutation = a change in the DNA base sequence
- substitution: one base swapped → changes ≤ 1 amino acid (sometimes none — degenerate code)
- deletion / insertion: shift the reading frame → change many later amino acids (frameshift)
- frameshift mutations usually have a much larger effect than a substitution
你掌握了
- 一个 突变 = DNA 碱基序列 的一个改变
- 替换:换掉一个碱基 → 改变 ≤ 1 个氨基酸(有时一个也不——简并密码)
- 缺失 / 插入:移动 阅读框 → 改变后面 许多 氨基酸(移码)
- 移码突变通常有比替换 大得多 的影响