Transcript Document
Cell Reproduction and Growth Cell Division M C Limits on Cell Size • Diffusion is more efficient over short distances • DNA limitations (has to be able to make proteins for whole cell) • Surface area – to – volume ratio Cell Reproduction • 1 somatic cell (parent cell) reproduces to make 2 identical somatic cells (daughter cells)… The Cell Cycle (phases in the life cycle of a cell) Interphase (G1, S, G2) Cell DivisionProphase Metaphase Anaphase Telophase Cytokinesis What happens in each of these phases of the cell cycle? Interphase • Cell grows in size and metabolizes • Chromosomes duplicated •G1-growth phase 1 •S-synthesis •G2-growth phase 2 1. Prophase • Chromatin coils up into chromosomes (Chromosomes are made up of 2 sister chromatids attached by a centromere) • Nucleus disappears • Centrioles move to poles • Spindle forms 2. Metaphase • Chromosomes attach to the spindle and line up on the equator of the cell. • Spindle fibers attach to each sister chromatid at the centromere. 3. Anaphase • Sister chromatids separate and move to opposite poles as spindle fibers shorten 4. Telophase • • • • Chromatids reach poles Chromosomes unwind Nuclei reform Spindle fibers break down 5. Cytokinesis • Division of the cytoplasm…separation of the 2 new cells Cytokinesis: Animal vs. Plant • Plasma membrane pinches in (cleavage furrow) • Cell is pinched in two • Cell plate laid down along equator • Plasma membrane forms around each cell • New cell walls form on each side of cell plate Summary Mitosis Check your BRAIN! 1. Describe how a cell’s surface area-tovolume ratio limits its size. 2. Why is it necessary for a cell’s chromosomes to be distributed to its daughter cells in such a precise manner? 3. How is the division of cytoplasm different in plants and in animals? 4. List the 4 phases of mitosis. • • • • • • • • • • • • • • Key Terms Chromosomes Chromatin Sister chromatids Centromere Spindle (spindle fibers) Centrioles Cleavage furrow Cell plate Interphase Prophase Metaphase Anaphase Telophase Cytokinesis