MITOSIS & CYTOKINESIS *centrioles – cylindrical shaped structures that make the spindle fibers *spindle fibers – cell structures that are made of microtubules and are involved in moving the chromosomes during cell division *Animal cells have 1 pair of centrioles. *Plant cells do not have centrioles, but they form a spindle that is almost identical to that of an animal cell.

Interphase: The cell is engaged in metabolic activity and preparing itself for mitosis. Chromosomes are not clearly visible. The DNA is copied during the Synthesis phase. centrioles

MITOSIS: Prophase: Chromosomes coil up and become visible centromere chromatid MITOSIS: Prophase: Chromosomes coil up and become visible during prophase. The nuclear membrane dissolves. Spindle fibers form. spindle fibers

Metaphase: During metaphase the chromosomes move to the center of the cell and line up along the equator. Spindle fibers link the chromatids of each chromosome to opposite poles.

Anaphase: Centromeres divide during anaphase. The two chromatids (now called chromosomes) move toward opposite poles as the spindle fibers attached to them shorten.

Telophase: A nuclear membrane forms around the chromosomes at each pole. Chromosomes, now at opposite poles, uncoil and the spindle fibers dissolve. Mitosis is complete.

CYTOKINESIS: As mitosis ends, cytokinesis begins. *In animal cells, the cell is pinched in half by a belt of protein threads. *In plant cells, a cell plate forms at the midline of the dividing cell and a new cell wall forms on both sides of the cell plate.

Animal vs. Plant Cell Belt of Proteins Cell Plate

Mitosis & Cytokinesis Animal Cell Plant Cell Interphase Prophase Metaphase Anaphase Telophase

Comparing Mitosis in Animal & Plant Cell

Mitosis in Onion Root Tips Interphase Early Prophase Late Prophase Metaphase Early Anaphase Late Anaphase Telophase Cytokinesis

Diploid: 2 sets of chromosomes (2n) Chromosomes visible