The Cell Cycle

G1 Phase Cellular growth & activity

S Phase DNA (chromosome) replication takes place 1 chromosome becomes a pair of “sister chromatids”

G2 Phase Final preparations for cell division Synthesis of organelles and materials

M Phase Period of time when mitosis takes place

Mitosis is the process by which the nucleus of the cell is divided into 2 nuclei, each with the same number and kinds of chromosomes as the parent cell.

Cytokinesis is the process by which the cytoplasm divides, thus forming 2 distinct cells.

Phases of Mitosis

Prophase a) Tighter coiling of the chromosomes - sister chromatids (chromosome) become visible as the chromatin condenses b) Centrioles separate

c) Spindle – consists of microtubules Originate from the centrioles and attach to the centromere of each chromatid d) Nucleolus disappears and the nuclear envelope breaks down

Metaphase Chromosomes line up across the equator (middle) of the cell

Anaphase a) Spindles pull apart the sister chromatids b) The 2 identical chromosomes move toward the opposite poles of the cell

Telophase Chromosomes begin to uncoil (decondense) into chromatin Nuclear envelope re-forms around the chromatin & the nucleolus becomes visible Cytokinesis begins to divide the cytoplasm