Cell Division - The process by which a cell divides Objectives: D2 - Describe the stages of the cell cycle including DNA replication, mitosis, and the importance of the cell cycle to the growth & repair of organisms D3 - Recognize that disruptions of the cell cycle can lead to cancer

Cell Cycle - the series of events that cells go through as they grow and divide Resting Growth DNA Replication Grows more in preparation for mitosis Mitosis (PMAT) & Cytokinesis

Cell Growth The larger a cell becomes, the more demands the cell places on its DNA. The cell also has trouble moving nutrients and wastes across the cell membrane. Small cells function more efficiently than large cells.

DNA Replication Copying process by which a cell duplicates its DNA DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing Each strand of the double helix of DNA serves as a template for the new strand

How Replication Occurs Enzymes unzip DNA by breaking the hydrogen bonds between the base pairs, which produces two replication forks DNA polymerase Joins individual nucleotides to make a new strand Proofreads each new strand

Mitosis consists of 4 phases Prophase Metaphase Anaphase Telophase

Cytokinesis Animal cells The cell membrane is drawn inward forming a cleavage furrow until the cytoplasm is pinched into 2 nearly equal parts Plant cells A cell plate gradually develops into a separating membrane.

Cell Cycle Regulators Cyclin a protein that regulates the timing of the cell cycle. Cancer Uncontrolled cell division of abnormal cells Cells do not enter the G o (resting) phase

Mitosis for growth & repair Chromosome Spindle fibers Centrioles

Etymology Mitosis: mitos- (Gk. warp thread) + -osis (L. act, process). So called because chromatin of the cell nucleus appears as long threads in the first stages.