6. CELL DIVISIONS

6.1 Cell cycle

6.2 Mitosis

• Chromosomes - each chromosome replicates during cell division to form an identical copy (chromatid). The chromatids of a pair are joined at the centromere
• Prophase - chromatin fibres condense and coil to form chromosomes, microtubules form spindle structure and nucleolus and nuclear envelope disappears
• Metaphase - chromosomes moved by spindle fibres to form metaphase plate in centre of the cell
• Anaphase - centromeres divide (pulled by centromeres) to separate chromatids to opposite poles of cell
• Telophase - separated chromatids are now chromosomes which assemble at each pole. Nuclear envelope reforms
• Cytokinesis - division of the cells
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6.3 Meiosis

Folie 4