Biol 241 - 2010 Lecture 1: Chromosome Assortment Mitosis...

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Biol 241 - 2010 Lecture 1: Chromosome Assortment – Mitosis and meiosis Nature of Chromosomes - In eukaryotic cells, DNA is complexed with histones into thin fibers. During mitosis and meiosis, these fibers coil and condense to form chromosomes. - Each chromosome contains one DNA molecule. - Genes are arranged on chromosomes. Mitosis - nuclear division associated with asexually dividing cells - in multi-cellular eukaryotes, mitosis occurs in somatic cells - maintaining constant set of chromosomes through cell generation. Cell Cycle G1 – S – G2 – M, progression regulated by cyclins and cyclin-dependent kinases (Cdk). Cell cycle regulation A) The level of cyclin oscillates with cell cycle. B) Checkpoints Stages of Mitosis A) Interphase – Interphase is the stage between successive mitoses. DNA replication actually occurs during the S (for “synthesis”) phase of the cell cycle. B) Prophase - Chromosomes condense and become visible. Centrosomes divide and move apart. Kinetochores become attached to the centromere , and microtubules become attached to the kinetochores. C) Metaphase - Nuclear envelope broken down, chromosomes highly condensed and lined up on the “metaphase plate” ( or “equatorial plate” ). D) Anaphase - Centromeres separate and the sister chromatids move to opposite poles of the celln. Chromatid=one, very long double-stranded DNA molecule. E)
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This note was uploaded on 02/09/2010 for the course BIOL 241 taught by Professor Henrychang during the Spring '10 term at Purdue University-West Lafayette.

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Biol 241 - 2010 Lecture 1: Chromosome Assortment Mitosis...

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