Cell Cycle *Cellular Division

Reproduction ●Asexual reproduction: generates offspring that are genetically identical to a single parent. Requires only one parent. (Mitosis) ●Sexual Reproduction: two parents contribute genetic information to produce unique offspring. (Meiosis)

Cell Cycle ●The cell cycle is the life cycle of a cell. Cells grow and divide, DNA/chromosomes replicate (S phase) and separate. ●Controlled by Stop” and “Go” proteins that signal the cell to stop or proceed through cell division. Checkpoints: G1 and G2. ●The cell cycle is divided into three distinct stages: interphase, mitotic phase and cytokinesis.

Interphase ●Interphase is a phase of the cell cycle, which cells spend the majority of time ●Cell is preparing for mitosis. ●DNA is in the form of chromatin ●Chromosomes are not visible.

Mitotic Phase or Mitosis

Details of Mitosis ●Mitosis produces two daughter cells, which each daughter cell will have a nucleus. ●Chromosomes in the cell nucleus, separated into two genetically identical sets of chromosomes (Nuclear Division) ●Eukaryotes use mitosis as a form of cellular division.(somatic cells) ●Prokaryotes use binary fission because there is no nucleus Interphase Mitosis: 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase Cytokinesis: produce two genetically identical daughter cells

1.Prophase ●Chromatin begin to condense and become visible as chromosomes. Why? ●Nucleolus disappears (Nuclear envelope dissolves) ●Centrioles move to opposite ends of cell and spindle fibers extend from centromere.

2. Metaphase ●Identical chromosomes (sister chromatids) align at the center of the cell. ●Spindle fibers connect each centromere of each chromosome to one centromere

3. Anaphase ●Sister chromatids separate. ●Microtubules form spindle fibers that attach to the centromere of each sister chromatid pulling them to opposite ends of the cell. The cell becomes elongated.

4.Telophase ●Chromatids arrive at opposite poles of cell ●Nuclear envelope forms around the daughter nuclei ●Chromosomes uncoil into chromatin ●Two identical nuclei exist ●END phase of MITOSIS

Cytokinesis ●Animals cells use actin to contract and pinch the cell into two daughter cells ●Cell is pinched at “cleavage furrow” ●Each with one nucleus ●Plant cells need a “cell plate” to be synthesized between the two daughter cells.

Mitotic and Cytokinesis Phases (phases of the cell cycle) results: ●The two identical cells go back into interphase. o Why? Replace old cells in multicellular organisms