1 6 cell division 2 - Lecture notes all PDF

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1.6 Cell Division

(http://www.cliffsnotes.com/sciences/biology/plant-biology/cell-division/eukaryote-cell-divison-the-cell-cycle)

New cells are formed from existing cells. - The cells that give rise to new cells are called parent cells. - The new cells are the daughter cells formed when the parent cell divides. The cell cycle describes the process. Nuclear division, or mitosis takes only small fraction of the cell cycle. During the rest of the cycle, genetic information is replicated. Stages of the cell cycle are: Interphase (G1, S, G2) Mitosis (P.MAT) Cytokinesis Interphase During interphase, the genetic material in the nucleus appears as chromatids. During the first part of interphase the cell grows and the organelles are replicated. Then, DNA copied. Each length of DNA forms a pair of strands. These strands are identical and are called sister chromatids. They are joined together at the centromere.

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Mitosis In mitosis a cell inherits two sets of chromosomes. This means the parent cell and the daughter cells are diploid. The symbol 2n represent this state, where n = the number in a set of chromosomes. Mitosis increases cell number in an organism. Growth and repair depends on mitosis, as does sexual reproduction in plants and animals. In Prophase 1. The nucleolus begins to fade. 2. The centrioles duplicate and move to opposite poles. 3. The centrioles form spindle fibers. 4. Chromosomes shorten and thicken, becoming visible. 5. The nuclear envelope begins to disintegrate. In Metaphase 1. Chromosomes line up along the equator of the cell. 2. One chromatid of each pair lies on either side. 3. Spindle fibers attach to the centromere. In Anaphase 1. The spindle fibers begin to contact. 2. Sister chromatids are pulled apart and move to opposite poles of the cell. In Telophase 1. Separation of chromatids is complete. 2. Spindle fibers disintegrate. 3. Each chromatid is now a chromosome. 4. The nuclear envelope reforms around each group of chromosomes. 5. The cell divides along the waist via cytokinesis. 6. Both daughter cells formed are identical. Cytokinesis  Cytoplasmic division– cell creates an actin furrow and divides...