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Published byMargaret Spinner Modified over 8 years ago
CELL DIVISION Unit 3 Part 2 – The Cell
Cell Cycles No nucleus No membrane bound organelles (ex. mitochondria, vacuole, chloroplast) A.) Cell division takes place in 2 steps: 1.) DNA is copied 2.) Cell splits by binary fission Contain a nucleus and organelles. Have a cell cycle Repeating sequence of growth and division Prokaryotic CellsEukaryotic Cells
Eukaryotic Cell Cycle 3 Stages: Interphase G1 – Growth S – DNA Synthesis G2 – Growth Mitosis – Division of Nucleus P – Prophase M – Metaphase A – Anaphase T – Telophase Cytokinesis Division of cytoplasm
Terms to know for Mitosis Chromatin The stringy, filamentous, working form of DNA. ReplicatChromosome One of the 2 copies of coiled DNA. ed Chromosome The 2 identical copies of a of DNA molecule attached by the centromere. Sister Chromatid 1 individual strand of the attached identical copies of DNA. Non-Replicated Chromosome Single strand of DNA; unattached and coiled. Spindle Fibers Fibers that are attached to centrioles to help pull apart chromosomes Centrioles Organelles that aid in pulling apart chromosomes Centromere Structure that holds the replicated chromosomes together
Sister Chromatids Replicated Chromosome Centromere Non-Replicated Chromosome Chromosome
Interphase G1 – first growth phase: The cell doubles in size and the organelles double. S – synthesis phase: the DNA that makes up the chromatin is copied (DNA replication) this is the longest phase of interphase. G2 – second growth phase: Growth and preparation for mitosis. This is when the cell functions as the type of cell it is and then prepares to divide. The LONGEST phase of the cell cycle. 90% of the cell’s life is spent in Interphase. The cell does not look unique. The nucleus and the nucleolus are visible; The nuclear membrane is intact and visible.
Interphase (G1, S, G2)
Mitosis (PMAT) Mitosis: The nucleus of a cell is divided into two nuclei with the same number of chromosomes (2n = diploid.) Consists of 4 phases Prophase Metaphase Anaphase Telophase
Prophase Longest phase of Mitosis. Chromatin coils and forms chromosomes. Nuclear envelope breaks down. Centrioles migrate toward opposite ends. Spindle fibers form and attach to the centromeres.
Metaphase Chromosomes line up in the middle of the cell.
Anaphase Centromeres of each chromosome split. Spindle fibers contract and separate the two sister chromatids pulling them to opposite poles. Each chromatid becomes a separate (non-replicated) chromosome in each daughter cell.
Telophase Last stage of Mitosis. Spindle fibers break down. Nuclear envelope reforms. Chromosomes at each pole uncoil and become chromatin.
Cytokinesis NOT part of mitosis. The cytoplasm divides into two cells. Cell membrane reforms. In plant cells the cell wall reforms and the cell membrane is laid down.
Video 1 Click the image to play the video segment. Video 1 Animal Cell Mitosis
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