14 The stage of mitosis division InterphaseMitotic phase / M phaseMitosisCytokinesis
15 Mitosis divisionInterphaseCellular metabolic activity is high , chromosomes and organelles are duplicated, and cell size may increase. Interphase accounts for 90% of the time of each cell cycle.G1 phaseS phaseG2 phase
16 Interphase G1 Phase: Growth--the cell grows in size. S Phase : Mitosis divisionInterphaseG1 Phase: Growth--the cell grows in size.S Phase :Prior to mitosis, the cell readies itself by duplicatingits chromosomes and other cellular contents Before DNA synthesis, the cell’s chromosomes consistof one chromatid After DNA synthesis, the cell’s chromosomes consistof dyads with 2 identical sister chromatids attached atthe centromere.G2 Phase :The cell prepares the enzymes and machinery for mitosis
22 Mitosis Prophase - Chromatin Chromosome (two sister chromatids) - Nuclear envelope breaks into fragments.- Microtublues Mitotic spindle.- Some of the spindle fibers reach the chromosomes and attachit.- Nonkinetochore microtubules overlap with those coming from the opposite pole
24 Metaphase Animal Cell Plant Cell The chromosomes align at the equitorial plate and are held in place by microtubules attached to the mitotic spindle and to part of the centromere.Animal CellPlant Cell
26 Anaphase Animal Cell Plant Cell During anaphase the mitotic spindle apparatus pulls the chromatids of each chromosome apart by attaching to each centromere. Note that the telomeres of each chromosome point toward the cell’s equator.Animal CellPlant Cell
27 Telophase Animal Cell Plant Cell Chromosomes begin to disperse. Spindle fibers disperse. The nuclear envelope forms again around the nuclei.Animal CellPlant Cell
28 CytokinesisCytokinesis begins--formation of daughter cells. In animals, like the whitefish, a cleavage furrow, a contractile ring of muscle like fibers, pinches the cell into two.
31 MeiosisSexual reproduction occurs only in eukaryotes. During the formation of gametes, the number of chromosomes is reduced by half, and returned to the full amount when the two gametes fuse during fertilization.Meiosis is a cell division process in organisms that sexually reproduce.