The Cell Cycle and Mitosis Cell Division in Prokaryotes Prokaryotes hav one circular chromosome Binary Fission- the division of a prokaryotic cell into two offspring cells DNA is copied, forming two identical chromosomes Cell grows until it reaches approximately twice the cell’s original size

Cell division in Eukaryotes Cell Cycle –repeating set of events in life of cell Interphase- time between cell divisions G1 phase- cells grow to mature size S phase- cell’s DNA is copied (synthesized) G2 phase- Time during which cell prepare fro cell division Cell Division: Mitosis- the nucleus of cell divides Cytokinesis- division of cell’s cytoplasm

Cell division in Eukaryotes https://wps. prenhall

Stages of Mitosis Prophase DNA condenses into chromosomes Centrosomes move to opposite poles Mitotic spindle starts to form

Metaphase Anaphase Chromosomes move to center of dividing cell Chromatids of each chromosome separate and move toward opposite poles

Telophase Spindle fibers disassemble Chromosomes return to a less tightly coiled chromatin state Nuclear envelope forms around each set of chromosomes Nucleolus forms in each of the newly forming cells

Cytokinesis- division of cytoplasm In Animal Cells Cytokinesis begins with a pinching inward of the cell; cleavage furrow Cleavage furrow pinches the one cell into two cells In Plant Cells Vesicles from Golgi apparatus join together at midline of dividing cell to form Cell Plate https://wps.prenhall.com/wps/media/objects/486/498658/CDA8_2/CDA8_2a/CDA8_2a.htm

Control of Cell Division Control occurs at 3 main checkpoints Cell growth (G1) checkpoint- if cell is healthy and has grown to suitable size during G1 phase, proteins initiate DNA synthesis (S phase) DNA synthesis (G2) checkpoint- DNA repair enzymes check the results of DNA replication. IF ok, then cell proceeds with mitosis Mitosis checkpoint- if cell passes this checkpoint, proteins signal the cell to exit mitosis. Cancer, the uncontrolled growth of cells is caused by mutations in the checkpoint proteins