🧬 Division cellulaire : Mitose & Méiose
Biologie cellulaire — partie 3 • 4 langues • exercices & schémas SVG
Raccourcis : 1 (All), 2 (FR), 3 (EN), 4 (ZH), 5 (KM)
FR — La reproduction cellulaire

Mitose : division équationnelle

La mitose produit deux cellules filles génétiquement identiques (2n → 2n). Phases : prophase, métaphase, anaphase, télophase. Utilisée pour la croissance, le renouvellement des tissus et la reproduction asexuée.

Prophase Métaphase Anaphase Télophase

Méiose : division réductionnelle

Deux divisions successives : méiose I (séparation des chromosomes homologues) et méiose II (séparation des chromatides). Résultat : 4 cellules haploïdes (n) génétiquement uniques → gamètes.

  • 🧬 Crossing-over (enjambement) : brassage génétique en prophase I
  • 🔁 Ségrégation indépendante : diversité des gamètes
🧬 Exercice 1 — Mitose vs Méiose

Combien de divisions cellulaires et combien de cellules filles produit la méiose ? À quoi sert la mitose ?

Méiose : 2 divisions → 4 cellules haploïdes. Mitose : 1 division → 2 cellules diploïdes identiques ; utilisée pour la croissance et le renouvellement.

🔁 Exercice 2 — Crossing-over

À quelle phase de la méiose se produit le crossing-over et quel est son avantage évolutif ?

Prophase I. Il crée de nouvelles combinaisons alléliques → diversité génétique, avantage pour l'adaptation.

EN — Cell division: mitosis & meiosis

Mitosis: equational division

One division → two identical daughter cells (2n → 2n). Stages: prophase, metaphase, anaphase, telophase. Role: growth, tissue repair, asexual reproduction.

Mitosis Meiosis I Meiosis II

Meiosis: reductional division

Two divisions: Meiosis I separates homologous chromosomes; Meiosis II separates sister chromatids. Produces 4 haploid cells (n) → gametes. Crossing-over during prophase I increases genetic diversity.

🧬 Exercise 1 — Key difference

What is the main difference between mitosis and meiosis regarding ploidy?

Mitosis maintains ploidy (2n → 2n). Meiosis reduces ploidy (2n → n).

🔁 Exercise 2 — Genetic variation

Name two mechanisms that generate genetic diversity during meiosis.

Crossing-over (prophase I) and independent assortment of homologous chromosomes in metaphase I.

中文 — 细胞分裂：有丝分裂与减数分裂

有丝分裂 (均等分裂)

一次分裂产生两个相同的子细胞 (2n → 2n)。用于生长、组织修复和无性繁殖。阶段：前期、中期、后期、末期。

有丝分裂 减数分裂

减数分裂 (减数分裂)

两次连续分裂：减数分裂I（同源染色体分离），减数分裂II（姐妹染色单体分离）→ 4个单倍体配子 (n)。交叉互换发生在前期I，增加遗传多样性。

🧬 练习1 — 染色体数目

人类细胞有46条染色体。经过有丝分裂后，子细胞有多少条染色体？经过减数分裂后，配子有多少条染色体？

有丝分裂 → 46条染色体（2n）。减数分裂 → 23条染色体（n）。

🔁 练习2 — 遗传重组

简述交叉互换发生在什么时期以及它的生物学意义。

发生在减数第一次分裂的前期 (prophase I)，增加配子的基因多样性，是进化的基础。

ភាសាខ្មែរ — ការបែងចែកកោសិកា (Mitosis & Meiosis)

មីតូស (Mitosis) ៖ ការបែងចែកស្មើ

មីតូសផលិតកោសិកាប្រភេទដូចគ្នាពីរ (2n → 2n)។ ដំណាក់កាល៖ ប្រូផេស (prophase) មេតាផេស (metaphase) អាណាផេស (anaphase) តេឡូផេស (telophase)។ សម្រាប់ការលូតលាស់ ជួសជុលជាលិកា និងបន្តពូជឥតភេទ។

មីតូស Meiosis I Meiosis II → 4 កោសិកា Haploid

ម៉ីយ៉ូស (Meiosis) ៖ ការបែងចែកកាត់បន្ថយ

ការបែងចែកពីរដង៖ Meiosis I (បំបែកក្រូម៉ូសូមដូចគ្នា), Meiosis II (បំបែកក្រូម៉ាទីតបងប្អូន) → បាន 4 កោសិកា Haploid (n) ជាហ្គាម៉ែត។ ការឆ្លងដូរ (crossing-over) ក្នុង Prophase I បង្កើនភាពចម្រុះហ្សែន។

🧬 លំហាត់ទី១ — ភាពខុសគ្នាសំខាន់

តើមីតូស និង ម៉ីយ៉ូស ខុសគ្នាត្រង់ចំនួនក្រូម៉ូសូមយ៉ាងដូចម្តេច?

មីតូស៖ 2n → 2n (ដូចគ្នា)។ ម៉ីយ៉ូស៖ 2n → n (កាត់បន្ថយពាក់កណ្តាល)។

🔁 លំហាត់ទី២ — ការប្រែប្រួលហ្សែន

តើយន្តការអ្វីខ្លះដែលបង្កើនភាពចម្រុះហ្សែនក្នុងម៉ីយ៉ូស?

Crossing-over (ការឆ្លងដូរ) និងការចាត់ចែងឯករាជ្យនៃក្រូម៉ូសូមដូចគ្នា (independent assortment)។