KEY CONCEPT Cells divide during mitosis and cytokinesis.

DNA + Histones form chromatin Chromosomes condense tightly for mitosis Chromosome Structure 1 long thread of DNA DNA wraps around proteins (histones) that condense it. DNA + Histones form chromatin Chromosomes condense tightly for mitosis DNA double helix DNA and histones Chromatin Supercoiled DNA

One half of a duplicated chromosome is a chromatid. DNA plus proteins is called chromatin. chromatid telomere centromere Condensed, duplicated chromosome One half of a duplicated chromosome is a chromatid. Sister chromatids are held together at the centromere. Telomeres protect DNA and do not include genes.

1. Interphase prepares the cell to divide. Mitosis and cytokinesis produce two genetically identical daughter cells. Parent cell centrioles spindle fibers centrosome nucleus with DNA 1. Interphase prepares the cell to divide. Copies DNA Cell grows Organelles are duplicated

Mitosis divides the cell’s nucleus in four phases. 2. Prophase: chromosomes condense nuclear envelope breaks down Spindle fibers form.

During metaphase, spindle fibers help chromosomes line up in the middle of the cell

4. Anaphase, sister chromatids separate to opposite sides of the cell.

5. Telophase: Nuclear membrane forms around chromosomes chromosomes begin to uncoil Spindle fibers fall apart

In animal cells, the membrane pinches closed. Cytokinesis differs in animal and plant cells. In animal cells, the membrane pinches closed. In plant cells, a cell plate forms.