AQA · A-Level · Biology

    Course version: 7402 · Version from Sept 2016

    Mitosis is the part of the cell cycle in which a eukaryotic cell divides…

    Full specification wording

    All cells arise from other cells: Mitosis is the part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA produced by the parent cell during DNA replication.

    Mitosis is nuclear division producing two daughter nuclei genetically identical to each other and to the parent nucleus.

    Checked against the AQA 7402 specification (opens in a new tab) on .

    • Point 4 of 14
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Mitosis is nuclear division producing two daughter nuclei genetically identical to each other and to the parent nucleus. It works only because DNA replication has already happened in interphase: every chromosome enters mitosis as two identical sister chromatids, and mitosis separates them, sending one complete set of chromatids to each pole. Because each daughter cell receives one chromatid from every chromosome, both end up with the same number of chromosomes as the parent cell and the same alleles, so mitosis is not a source of genetic variation. Its biological roles are growth, repair and replacement of worn-out cells, and asexual reproduction. Contrast it with meiosis, met later in the course, which involves two divisions, produces four genetically different haploid cells, and does generate variation through crossing over and independent segregation.

    What earns the marks

    • Two daughter cells being produced, each genetically identical to the parent cell and to each other.
    • The chromosome number being maintained because replicated sister chromatids are separated, one of each pair going to each cell.
    • Placing mitosis in eukaryotic cells and linking it to replication of linear DNA.
    • A correct role: growth, repair, replacement of cells or asexual reproduction.
    • Stating that the identical copies were made by the parent cell during DNA replication in interphase.

    Common mistakes and how to put them right

    • Saying mitosis produces four daughter cells or haploid cells, importing meiosis into the answer.

    • Claiming mitosis halves or doubles the chromosome number.

    • Treating mitosis as the whole cell cycle rather than the nuclear division within it.

    • Writing that mitosis creates genetic variation.

    • Saying the daughter cells are similar rather than genetically identical.

    Exam tips

    • Use the words genetically identical; similar and the same are both too weak for the mark.
    • If a table contrasts mitosis with binary fission, tick two daughter cells for both and reserve linear DNA and eukaryotic cells for mitosis.
    • Mention interphase replication whenever you explain why the daughter cells are identical; it is the reason, not an aside.

    Try the lesson

    The start of the All cells arise from other cells: Mitosis is the part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA produced by the parent cell during DNA replication. lesson, made from checked teaching notes for this specification point.

    Have a go first

    How many daughter cells are produced when one eukaryotic cell divides by mitosis?

    Listen

    Mitosis is nuclear division producing two daughter nuclei genetically identical to each other and to the parent nucleus. It works only because DNA replication has already happened in interphase: every chromosome enters mitosis as two identical sister chromatids, and mitosis separates them, sending one complete set of chromatids to each pole. Because each daughter cell receives one chromatid from every chromosome, both end up with the same number of chromosomes as the parent cell and the same alleles, so mitosis is not a source of genetic variation. Its biological roles are growth, repair and replacement of worn-out cells, and asexual reproduction. Contrast it with meiosis, met later in the course, which involves two divisions, produces four genetically different haploid cells, and does generate variation through crossing over and independent segregation. A strong answer earns marks for these points. two daughter cells being produced, each genetically identical to the parent cell and to each other. the chromosome number being maintained because replicated sister chromatids are separated, one of each pair going to each cell. placing mitosis in eukaryotic cells and linking it to replication of linear DNA. a correct role: growth, repair, replacement of cells or asexual reproduction. Exam tip: Use the words genetically identical; similar and the same are both too weak for the mark.

    See it

    A top-down flowchart. A parent eukaryotic cell leads to DNA replication in interphase, which leads to every chromosome entering mitosis as two identical sister chromatids. This leads to mitosis, described as nuclear division, which leads to one chromatid from every chromosome going to each pole. This produces two daughter cells, which lead to two outcomes: they are genetically identical to each other and to the parent cell, and they have the same chromosome number as the parent cell.
    It shows how DNA replication in interphase followed by mitosis gives two genetically identical daughter cells with the same chromosome number as the parent.

    Key words

    Say what each word means before you turn the card.

    mitosis

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    genetically identical daughter cells

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    chromosome number maintained

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    growth, repair and asexual reproduction

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    See every definition
    mitosis
    The part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with identical copies of DNA produced during DNA replication.
    genetically identical daughter cells
    Two daughter cells that each receive one chromatid from every chromosome, so both end up with the same alleles as the parent cell.
    chromosome number maintained
    Each daughter cell receives one chromatid from every chromosome, so both end up with the same number of chromosomes as the parent cell.
    growth, repair and asexual reproduction
    The biological roles of mitosis, including replacement of worn-out cells.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-down flowchart. A parent eukaryotic cell leads to DNA replication in interphase, which leads to every chromosome entering mitosis as two identical sister chromatids. This leads to mitosis, described as nuclear division, which leads to one chromatid from every chromosome going to each pole. This produces two daughter cells, which lead to two outcomes: they are genetically identical to each other and to the parent cell, and they have the same chromosome number as the parent cell.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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