The significance of mitosis
Introduced| English | Meaning |
|---|---|
| mitosis/maɪˈtəʊsɪs/ | Nuclear division that produces two genetically identical nuclei with the same chromosome number as the original nucleus. |
| genetically identical/dʒɪˈnetɪkli aɪˈdentɪkl/ | genetically identical |
| tumour/ˈtjuːmə/ | An abnormal growth of cells forming a mass, which may be benign or malignant. |
| asexual reproduction/eɪˈsekʃuːəl rɪprəˈdʌkʃn/ | Reproduction without the fusion of gametes, normally producing genetically identical offspring except for mutations. |
| stem cell/stem sel/ | Unspecialised. |
| unspecialised/ʌnˈspeʃəlaɪzd/ | unspecialised |
| differentiate/ˌdɪfəˈrenʃɪeɪt/ | For a cell, to develop specialised structures and functions from a less specialised state. |
Why mitosis 有丝分裂 matters
- Mitosis is nuclear division that makes two genetically identical 遗传上相同 daughter cells.
- Identical copies are exactly what a body needs to grow and repair itself.
- But the same process, out of control, causes tumours 肿瘤.
Why mitosis matters
Classify real cases by the role mitosis is playing.
The two daughter cells produced by mitosis are:
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Mitosis produces genetically identical cells — they carry exactly the same genes as the parent.
Mitosis produces genetically identical daughter cells, which is why it is used for growth and repair.
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Identical copies are exactly what growth, repair and asexual reproduction need.
What mitosis is for
- growth of a multicellular organism (more cells).
- replacement of dead or damaged cells.
- repair of tissues by making new cells.
- asexual reproduction 无性生殖 — one parent producing identical offspring.
Each new cell carries exactly the same genes as the parent.
The mitotic cell cycle: interphase then mitosis and cytokinesis
Select all the roles of mitosis.
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Mitosis gives identical cells for growth, repair/replacement and asexual reproduction. Varied gametes come from meiosis; ATP comes from respiration.
Match each role of mitosis to an example.
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All of these need genetically identical cells, so all use mitosis.
Stem cells 干细胞
- A stem cell is an unspecialised 未分化 cell that can:
- keep dividing by mitosis, and
- differentiate 分化 (change) into specialised cell types.
- They are the source of new cells for replacing losses and repairing tissues.
A stem cell can keep dividing or differentiate into many specialised cell types
A stained onion root tip: several cells are caught dividing
An unspecialised cell that can keep dividing and differentiate into other cell types is a ______ cell.
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Stem cells are unspecialised; they divide by mitosis and can differentiate into specialised cells.
When control is lost
- The cell cycle is normally tightly controlled, so cells divide only when needed.
- If that control is lost, a cell divides again and again without stopping.
- This uncontrolled division produces a lump of cells — a tumour.
When cell-cycle control is lost, a cell divides over and over, building up into a tumour
A tumour forms when:
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Losing cell-cycle control lets cells divide without stopping, building up into a tumour.
You've got it
- mitosis → two genetically identical daughter cells (same genes)
- used for growth, replacement, repair, asexual reproduction
- stem cell = unspecialised; divides by mitosis and differentiates
- losing cell-cycle control → uncontrolled division → a tumour