Anandan-1.14_lecture_2011

Anandan-1.14_lecture_2011 - BIO 122-A Dr. Shivanthi Anandan...

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BIO 122-A Dr. Shivanthi Anandan Outline 14.1 The Eukaryotic cell cycle 14.2 Mitotic Cell division 14.3 Meiosis and sexual reproduction 14.4 Variation in chromosome structure and number 13.3 Cancer 1 Anandan BIO 122-A Fall 2011
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Cell division Reproduction of cells Highly regulated series of events 2 types in eukaryotes Mitosis Meiosis Prokaryotes Binary fission 2 Anandan BIO 122-A Fall 2011
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Eukaryotic chromosomes Cytogenetics – field of genetics involving microscopic examination of chromosomes and cell division When cells get ready to divide, the chromosomes compact enough to be seen with a light microscope Karyotype reveals number, size, and form of chromosomes in an actively dividing cell 3 Anandan BIO 122-A Fall 2011
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Sets of chromosomes Humans have 23 pairs of chromosomes or 46 total chromosomes Autosomes – 22 pairs in humans Sex chromosomes – 1 pair in humans XX or XY Ploidy Diploid or 2n – humans have 23 pairs of chromosomes Haploid or n – gametes have 1 member of each pair of chromosomes or 23 total chromosomes 4 Anandan BIO 122-A Fall 2011
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Homologous In diploid species, members of a pair of chromosomes are called homologues They are homologous chromosomes Each homologue nearly identical in size and genetic composition Both carry gene for eye color but one may have brown and the other blue Sex chromosomes are very different from each other - X and Y differ in size and composition 5 Anandan BIO 122-A Fall 2011
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6 Anandan BIO 122-A Fall 2011
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7 Cell cycle G 1 – first gap S – synthesis of DNA Interphase G 2 – second gap M – mitosis and cytokinesis G 0 – substitute for G 1 for cells postponing division or never dividing again Anandan BIO 122-A Fall 2011
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8 Anandan BIO 122-A Fall 2011
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G 1 phase Cell accumulates molecular changes that cause progression through the cell cycle Passes restriction point where cell is committed to enter S phase Chromosomes replicate during S phase forming sister chromatids 9 Anandan BIO 122-A Fall 2011
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S phase Chromosomes replicate After replication, 2 copies stay joined to each other and are called sister chromatids Human cell in G 1 has 46 chromosomes Same cell in G 2 (after S) has 46 pairs of sister chromatids or 92 chromatids 10 Anandan BIO 122-A Fall 2011
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11 Anandan BIO 122-A Fall 2011
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G 2 Cell synthesizes proteins needed during mitosis and cytokinesis M phase – mitosis Divide one cell nucleus into two Cyokinesis Division of cytoplasm, follows in most cases 12 Anandan BIO 122-A Fall 2011
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13 Decision to divide External factors Environmental conditions Signaling molecules Internal factors Cell cycle control molecules Checkpoints Anandan BIO 122-A Fall 2011
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Checkpoint proteins Cyclins and cyclin-dependent kinases = (cdks) responsible for advancing a cell through the phases of the cell cycle Amount of cyclins varies through cycle
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This note was uploaded on 01/15/2012 for the course BIOLGOY 122 taught by Professor Anandan during the Spring '11 term at Drexel.

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Anandan-1.14_lecture_2011 - BIO 122-A Dr. Shivanthi Anandan...

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