BIO311C_F07_cell cycle - Cell cycle and regulation Pages...

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Unformatted text preview: Cell cycle and regulation Pages 218-232 Phases of the Cell Cycle The cell cycle consists of Interphase Mitotic phase INTERPHASE G 1 S (DNA synthesis) G 2 C y t o k i n e s i s M i t o s i s M I T O T I C ( M ) P H A S E Figure 12.5 The stages of interphase G1 stage cell growth, accumulates materials for DNA synthesis. S stage DNA synthesis occurs, and DNA replication results in duplicated chromosomes. G2 stage cell synthesizes proteins needed for cell division S phase Each duplicated chromosome Has two sister chromatids, which separate during cell division 0.5 m Chromosome duplication (including DNA synthesis) Centromere Separation of sister chromatids Sister chromatids Centromeres Sister chromatids A eukaryotic cell has multiple chromosomes, one of which is represented here. Before duplication, each chromosome has a single DNA molecule. Once duplicated, a chromosome consists of two sister chromatids connected at the centromere. Each chromatid contains a copy of the DNA molecule. Mechanical processes separate the sister chromatids into two chromosomes and distribute them to two daughter cells. Figure 12.4 G2 of Interphase: G2 of Interphase: 1)Two centrosomes 2)Each contains 2 centrioles (animal) 3)Nucleus with envelope seen 4)One or more nucleoli nucleus Centrioles Microtubules Centrosome cytoplasm cytoplasm Centrosomes and Centrioles Centrosome microtubule organizing center Centrioles pair present with in centrosome 1) Gradual condensation of chromosomes 2) Sister chromatids 3) Nucleoli begin to break down and disappear Outside nucleus Prophase chromosomes condense Prophase chromosomes condense Asters (short microtubules) Prometaphase Prometaphase 1) degradation of nuclear envelope 2) microtubules extend from each centrosome toward middle of cell attach to kinetochore on chromosome 3) kinetochore of unattached sister chromatid associates with microtubules from opposite centrosome 4) two sister chromatids oriented - opposite poles (stable arrangement) Prophase ends when kinetochore of each sister chromatid each sister chromatid is attached to microtubule from centrosome of opposite pole Site at which chromosome is attached to microtubule chromatin nucleolus nucleus centrioles condensing chromosomes Metaphase middle stage...
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BIO311C_F07_cell cycle - Cell cycle and regulation Pages...

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