Meiosis · 减数分裂
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| meiosis/meɪˈəʊsɪs/ | 减数分裂 | jiǎn shù fēn liè |
| diploid/ˈdɪplɔɪd/ | 二倍体 | èr bèi tǐ |
| haploid/ˈhæplɔɪd/ | 单倍体 | dān bèi tǐ |
| gamete/ˈɡæmiːt/ | 配子 | pèi zi |
Making sex cells
- Body cells divide by mitosis to make identical copies.
- But sex cells — sperm and eggs — need something different.
- When two of them join, the chromosome number must stay correct.
- The special division that makes them is called meiosis.
制造生殖细胞
- 体细胞通过有丝分裂来制造相同的拷贝。
- 但生殖细胞——精子和卵子——需要不一样的东西。
- 当两个它们结合时,染色体数目必须保持正确。
- 制造它们的那种特殊分裂,叫做减数分裂。
Diploid and haploid
- Most of your cells are diploid 二倍体 — two sets of chromosomes, one from each parent.
- A gamete 配子 (sperm or egg) must be haploid 单倍体 — just one set.
- That way, sperm and egg together rebuild the full double set.
- Meiosis is what halves the chromosome number to make gametes.
二倍体与单倍体
- 你大多数细胞是二倍体(diploid)——两套染色体,每个亲本一套。
- 一个配子(gamete)(精子或卵子)必须是单倍体(haploid)——只有一套。
- 这样,精子和卵子一起才能重建完整的双套。
- 减数分裂就是把染色体数目减半来制造配子的过程。
What does meiosis produce? · 减数分裂产生什么?
Meiosis · 减数分裂 makes gametes — sex cells with half the normal chromosome number. · 减数分裂产生配子——染色体数目为正常一半的生殖细胞。
Meiosis: divide by two, twice
- Meiosis 减数分裂 makes gametes by dividing twice.
- First the DNA is copied, once.
- Meiosis I separates the matching pairs of chromosomes.
- Meiosis II separates the sister chromatids — giving four haploid gametes.
减数分裂:除以二,两次
- 减数分裂(meiosis)通过分裂两次来制造配子。
- 首先 DNA 被复制,一次。
- 减数分裂 I 分开配对的染色体。
- 减数分裂 II 分开姐妹染色单体——产生四个单倍体配子。
How meiosis halves the chromosomes · 减数分裂如何把染色体减半
Step through meiosis — one cell divides twice to make four gametes, each with half the chromosome number. · 一步步走过减数分裂——一个细胞分裂两次,产生四个配子,每个染色体数目减半。
A haploid cell has… · 单倍体细胞有……
A haploid cell has one set; a diploid body cell has two. Gametes are haploid. · 单倍体细胞有一套;二倍体体细胞有两套。配子是单倍体。
Human body cells have 46 chromosomes. How many are in a human gamete? · 人的体细胞有 46 条染色体。一个人的配子里有多少条?
Meiosis halves 46 to 23, so a sperm or egg carries 23 chromosomes. · 减数分裂把 46 减半为 23,所以一个精子或卵子携带 23 条染色体。
Fertilization restores the set
- A haploid sperm joins a haploid egg at fertilization.
- One set plus one set makes a full diploid cell again.
- That first cell then grows by mitosis into a whole organism.
- Meiosis and fertilization keep the chromosome number stable across generations.
受精恢复整套
- 一个单倍体精子在受精时与一个单倍体卵子结合。
- 一套加一套,又组成一个完整的二倍体细胞。
- 那第一个细胞随后通过有丝分裂长成一个完整的生物体。
- 减数分裂和受精让染色体数目在世代间保持稳定。
Meiosis involves two divisions, producing four cells from one. · 减数分裂包含两次分裂,从一个细胞产生四个。
Meiosis I and meiosis II together split one cell into four haploid gametes. · 减数分裂 I 和减数分裂 II 一起把一个细胞分成四个单倍体配子。
Select all · 所有 true statements about meiosis. · 选出关于减数分裂的所有正确说法。
Making two identical body cells is mitosis, not meiosis. The other three are correct. · 产生两个相同的体细胞是有丝分裂,不是减数分裂。其余三条正确。
Do not confuse meiosis with mitosis. Mitosis makes two identical, full (diploid) cells. Meiosis makes four gametes with half the chromosomes (haploid). Same start, very different results — remember: meiosis reduces.
不要把减数分裂和有丝分裂搞混。有丝分裂产生两个相同的、完整的(二倍体)细胞。减数分裂产生四个染色体减半的配子(单倍体)。同样的起点,非常不同的结果——记住:减数分裂减少。
Human chromosome maths:
- Your body cells each hold 46 chromosomes (diploid).
- Meiosis halves this, so each sperm or egg has 23 (haploid).
- At fertilization, $23 + 23 = 46$ — the full set is restored in the new cell.
人类染色体的算术:
- 你的体细胞每个持有 46 条染色体(二倍体)。
- 减数分裂把它减半,所以每个精子或卵子有 23 条(单倍体)。
- 受精时,$23 + 23 = 46$——完整的一套在新细胞里被恢复。
Meiosis makes haploid gametes from a diploid cell by dividing twice, halving the chromosome number. At fertilization two gametes combine to restore the full diploid set, keeping the chromosome number stable from one generation to the next.
减数分裂通过分裂两次,从一个二倍体细胞制造单倍体****配子,把染色体数目减半。受精时两个配子结合,恢复完整的二倍体套,让染色体数目从一代到下一代保持稳定。