Cell Division Section 8.2

All cells are derived from the division of pre-existing cells Cell division is the process by which cells produce offspring cells

Cell division in Prokaryotes Binary fission- the division of a prokaryotic cell into 2 offspring cells

Cell division in Eukaryotes Mitosis- results in new cells with genetic material that is identical to that of the original cell Meiosis- reduces the chromosome number by half in new cells

The cell cycle The repeating set of events that make up the life of a cell Interphase- the time between cell divisions M phase- mitosis Cytokinesis- the division of the cytoplasm of the cell

Interphase G 1 phase-offspring cells grow to mature size S phase- the cell’s DNA is copied G 2 phase- the time gap following the S phase and preceding cell division G 0 phase- cells do not copy their DNA and don’t prepare for cell division

Mitosis Divided into 4 phases: prophase, metaphase, anaphase, and telophase

Prophase First phase of mitosis Centrosomes- appear next to the disappearing nucleus Centrioles- found in animal cells

Spindle fibers- made of microtubles radiate from the centrosomes in preparation for mitosis Mitotic spindle- equally divides the chromatids between the 2 offspring cells

Kinetochore fibers- attach to kinetochore Kinetochore- disk-shaped protein Polar fibers- extend across the dividing cell from centrosome to centrosome

Metaphase Second phase of mitosis The kinetochore fibers move the chromosomes to the center of the dividing cell

Anaphase Third stage of mitosis Chromatids of each chromosome separate at the centomere

Telophase Fourth stage of mitosis Spindle fibers disassemble Chromosomes return to a less tightly coiled chromatin state

Cytokinesis Cleavage furrow- pinches the cell into 2 cells (animal cells) Cell plate- membrane-bound cell wall (plant cells)