Mitosis and the Cell cycle

What happens during: Interphase

• no chromosomes visible

• DNA histones and centrioles all replicated in preparation for cell divisions

What happens during: Prophase

• Chromosomes condensed and visible

• Centrioles at opposite poles of cell

• Nucleolus disappears

What happens during: Metaphase

• Nuclear envelope disappears

• Chromosomes align along equator of the cell

• Spindle fibres (microtubules) - attached to centromere - connect centrioles to chromosomes

What happens during: Anaphase

• Centromeres split, allowing chromatids to separate

• Chromatids move towards poles, centromeres first, pulled by motor proteins “walking” along the microtubule tracks

What happens during: Telophase

• Spindle fibres disperse

• Nuclear envelope forms

• Chromatids uncoil and become too thin to see

What happens during: Cytokinesis

• In all animal cells a ring of actin (proteins) filaments forms round the equator of the cell, and then tightens to form a cleavage furrow, which splits the cell in two

• In the plant cell vesicles move to the equator, line up and fuse to form two membranes called the cell plate. A new cell wall is laid down between membranes, which fuses with the existing cell wall