Chapter 12

Chapter 12 - 1 of 5 Chapter 12 The Cell Cycle Cell division...

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1 of 5 Chapter 12: The Cell Cycle Cell division involves distribution of identical genetic material (DNA) to two daughter cells A dividing cell duplicates its DNA, allocating the two copies to opposite ends and then splitting into two daughter cells Genome: genetic information of a cell DNA molecules are packaged into chromosomes, which are made up of chromatin (complex of DNA and associated protein molecules) Nuclei of human somatic cells have 46 chromosomes (2 sets of 23), and gametes have 23 Each duplicated chromosome has two sister chromatids that then separate Mitosis (division of nucleus) is usually followed by cytokinesis (division of the cytoplasm) Phases of the Cell Cycle o Mitotic (M) Phase includes both mitosis and cytokinesis o Interphase (cell growth and copying of chromosomes in preparation for cell division) 90% of the cycle G1 phase, S phase (chromosomes are copied), G2 phase Cell grows by producing proteins and organelles Mitosis: Prophase, Prometaphase, Metaphase, Anaphase, Telophase Mitotic Spindle: begins to form during prophase, fibers made of microtubules and proteins o Gain and lose subunits of tubulin to grow and shorten o Assembly of spindle microtubules starts at the centrosome (organizes microtubules) o Pair of centrioles is located at the center of the centrosome, but not key to cell division o During interphase, the centrosome replicates, forming two centrosomes, move apart during prophase and prometaphase and spindle microtubules grow from them o Aster- radial array of short microtubules extends from each centrosome
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2 of 5 o Kinetichore- each of two sister chromatids has a kinetichore, structure of proteins associated with specific sections of chromosomal DNA at the centromere, spindle fibers attach to kinetichores (kinetichore microtubules) during prometaphase
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This note was uploaded on 09/28/2010 for the course BISC 220 taught by Professor Mcclure during the Spring '09 term at USC.

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Chapter 12 - 1 of 5 Chapter 12 The Cell Cycle Cell division...

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