Hrincevich_CH_12_ADDITIONAL_MATERIAL_student_outline

Hrincevich_CH_12_ADDITIONAL_MATERIAL_student_outline -...

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Chromosomes and Human Genetics Chapter 12 (Additional Topics: no additional  readings, but focus on THIS lecture  material for exam questions)
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Some genes on chromosomes control cell  growth and division  If something affects chromosome structure at or  near these loci, cell division may spiral out of  control   This can lead to cancer
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  Philadelphia Chromosome First abnormal chromosome to be associated  with a cancer  Reciprocal translocation of chromosome  pieces; #9 had piece of #22 attached to it Abnormal protein produced as a result  Causes chronic myelogenous leukemia (CML) 
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Re-examining Mendel’s Work By 1882, Flemming observed threadlike  chromosomes in nuclei of dividing cells  By 1887, Weisman suggested that meiosis  halves the # of chromosomes when gametes are  produced   By 1900, Mendel’s work finally appreciated
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  Homologous Chromosomes Homologous autosomes (non-sex  chromosomes) are identical in length,  size, shape, and gene sequence  Sex chromosomes are non-identical but  still homologous   Homologous chromosomes interact,  then segregate from one another during  meiosis
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Alleles Different molecular forms of a gene   Arise through mutation Diploid cell has a pair of alleles at each  locus   Alleles on homologous chromosomes  may be same or different 0
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a b c a b c A B C A B C A B C a b c a b c b c A A B C B C a 0 How Crossing Over Creates New Allele Combinations in Gametes
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Sex Chromosomes Discovered in late 1800s  Mammals, fruit flies   XX is female, XY is male  In other groups XX is male, XY female Human X and Y chromosomes function  as homologues during meiosis  0
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Karyotype Preparation - Stopping  the Cycle   Cultured cells are arrested at metaphase  by adding colchicine   This is when chromosomes are most  condensed and the easiest to identify 0
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  Karyotype Preparation Arrested cells are broken open  Metaphase chromsomes are fixed  and stained  Chromosomes are photographed  through microscope Photograph of chromosomes is cut  up and arranged to form karyotype  diagram  0
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0
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0 Karyotype.swf (use Apple Quicktime to open and view)
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Sex  Determination   X X Y X XX XY XX XY X X Y X x x eggs sperm female (XX) male (XY) 0
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0 Sex Determination.swf (use Apple Quicktime to open and view)
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  The Y Chromosome Fewer than two dozen genes identified  on the Y  One is the master gene for male sex  determination  SRY gene (sex-determining region of Y)   SRY present, testes form SRY absent, ovaries form  0
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Chromosome 10 weeks Y present Y absent 7 weeks birth approaching appearance of structures that will give rise to
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This note was uploaded on 02/25/2010 for the course BIOL 1001 taught by Professor Minor during the Fall '08 term at LSU.

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Hrincevich_CH_12_ADDITIONAL_MATERIAL_student_outline -...

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