Cell Division

Why do cells divide? For an organism to grow → add more cells To replace lost or damaged cells The result is two cells genetically identical to one another

Specialized Structures  Organelles that appear only for division o Centrioles Two sets that help to anchor the spindle fibers on each end o Spindle Fibers Fibers that attach to chromosomes and pull them around the cell o Centromeres Attach two sister chromatids together during early part of cell division

Strands of DNA Genetic material of the cell takes different forms throughout cell cycle  Chromatin – unwound strands of DNA; before and after mitosis  Chromosomes – rod-like (coiled) strands of DNA; appear during mitosis  Chromatids – identical copies of chromosomes; make chromosome pairs

Tracking Chromosomes Each new cell will have the same type and number of chromosomes Example – each human cell has 46 chromosomes, therefore each new cell after cell division will also have 46 chromosomes

Example # of Chromosomes Important PointsStage/Phase 46Chrom. Duplicate (Replication)Interphase 92Mitosis beginsProphase 92 Chrom. pairs line up in center of cell Metaphase 92 Chrom. pairs split and begin moving to opposite ends Anaphase 92 Two new nuclei form, each with a full set of chrom. (Mitosis ends) Telophase 46 x 2 The cytoplasm and remaining organelles split resulting in two new cells identical to each other and the original Cytokinesis

Cell Cycle Flash Cards