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Microscope Cell Division Investigation

Choose a prepared slide, then use the microscope to search for cells at each stage of mitosis or meiosis. Start at low power to find where the dividing cells are, then move up to high power to identify them.

Slide tray

    How the microscope works

    • Move the slide: drag the field, or use WASD / the arrow keys.
    • Objectives: 4× (40× total), 10× (100×), 40× (400×) — keys 1 2 3. Higher power shows more detail but a thinner slice is in focus.
    • Focus: drag or scroll the knobs, or press Q/E (fine) and Shift+Q/E (coarse). Coarse focus is locked at 400×. Each cell sits at a slightly different depth, so refocus on the cell you are studying.
    • Light: too much light washes out contrast at high power; too little makes it too dark.
    • Answer: pick a task, put the cell in the centre of the field (or point at it), focus it (bar above 75%), then click it or press Enter.
    • A wrong answer costs 1 point and 5 seconds (or ends the lab in Hardcore). Each task has a ? hint, and the Glossary explains the terms. Answering fast earns a bonus point.

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    Glossary

    Chromatid / sister chromatids
    One copy of a chromosome. After DNA is copied, each chromosome is two identical sister chromatids joined at the centromere.
    Centromere
    The pinched region where sister chromatids are joined. Spindle fibres attach here (at the kinetochore).
    Homologous chromosomes (homologs)
    A pair of chromosomes, one from each parent, that carry the same genes in the same order.
    Tetrad (bivalent)
    A pair of homologs held together in prophase I. It has four chromatids in all (two chromosomes, each with two sister chromatids).
    Crossing over
    Two non-sister chromatids of a homologous pair break and swap matching segments in prophase I, making new combinations of genes.
    Chiasma (plural: chiasmata)
    The X-shaped crossing point where crossing over has happened. Chiasmata hold the homologs together until anaphase I.
    Spindle
    Fibres (microtubules) that pull chromosomes apart. The poles are at the two ends; the plate (equator) is the middle plane at right angles to the spindle.
    Centriole / centrosome
    Animal cells organise the spindle from centrosomes containing a pair of centrioles. Plant cells have no centrioles.
    Cleavage furrow / cell plate
    How the cytoplasm divides: animal cells pinch in a cleavage furrow; plant cells build a cell plate across the middle that becomes a new wall.
    Diploid (2n) and haploid (n)
    Diploid cells have two of each chromosome (in this lab 2n = 4). Haploid cells have one of each (n = 2), as in gametes.
    Model view colours
    maternal pair 1   paternal pair 1 (banded)   maternal pair 2   paternal pair 2 (banded). A chromatid showing two colours has swapped a piece by crossing over. Stain view does not colour-code homologs, like a real slide.