Meiosis
Introduced| English | Meaning |
|---|---|
| gametes/ˈɡæmiːts/ | Haploid reproductive cells that fuse during fertilisation to form a zygote. |
| meiosis/meɪˈəʊsɪs/ | A type of nuclear division that produces haploid nuclei with half the original chromosome number and creates genetic variation. |
| variation/ˌveərɪˈeɪʃn/ | Differences in characteristics between individuals or values within a set. |
Making gametes 配子
- Gametes must carry only half the chromosomes, so that fertilisation restores the full set.
- The special division that does this is meiosis 减数分裂.
Meiosis produces how many cells from one parent cell?
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Meiosis makes four gametes.
Each cell made by meiosis has:
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Gametes carry half the chromosomes.
Meiosis produces the sex cells, also called ______.
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Gametes have half the chromosome number.
What meiosis is
- Meiosis produces four cells, each with half the chromosome number.
- These cells are the gametes (sperm and eggs).
A Punnett square for Bb x Bb gives a 3:1 ratio of dominant to recessive
Meiosis
Meiosis makes gametes — four cells, each with HALF the chromosomes and all different.
Meiosis is important because it:
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Meiosis mixes genes, producing variation.
It creates variation 变异
- Meiosis mixes the genes, so each gamete is genetically different.
- This is a major source of variation in sexual reproduction.
Halving the chromosome number stops it doubling each generation.
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Fertilisation then restores the full number.
Mitosis vs meiosis
- Mitosis: 2 identical cells, full chromosome number — growth/repair.
- Meiosis: 4 varied cells, half the number — making gametes.
Meiosis halves the chromosome number; mitosis keeps it the same. This halving is essential — without it, the chromosome number would double every generation at fertilisation.
You've got it
- meiosis makes four cells, each with half the chromosome number — the gametes
- it mixes genes, creating variation
- mitosis = 2 identical (full number); meiosis = 4 varied (half number)