Lect3 - Bridges and Triploids White XwXwY XY Y YY Y lethal...

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1 Bridges and Triploids White X w X w Y X Y Y X w X w X w X w Y W Y W YY lethal Y X w X w white female Y X w White male Y X w Y White male
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2 Triploidy Species that are triploid, reproduce asexually (plant species) What are the consequences of triploidy during mitosis and meiosis? Haploid Diploid Triploid Mitosis
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3 Triploidy Species that are triploid, reproduce asexually (plant species) What are the consequences of triploidy during mitosis and meiosis? Haploid Diploid Triploid Mitosis
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4 Meiosis and triploids MeiosisI This is for one chromosome. If there are n chromosomes in an organism, then balanced  gametes (equal copies of all chromosomes) are very rare.
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5 Meiosis and triploids 4N 3N 3N 2N Triploids produce unbalanced  gametes MeiosisI This is for one chromosome. If there are n chromosomes in an organism, then balanced  gametes (equal copies of all chromosomes) is very rare.
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6 Seedless watermelons Triploidy is useful in agriculture.  Biological control: Cross a tetraploid watermelon with a diploid watermelon
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7 And triploid toads Triploid toads Nature Genetics  30, 325 - 328 (2002)  Tetraploid green toads reproduce through diploid eggs and sperm cells. A new taxon was discovered at an isolated site in the Karakoram mountain range. Every wild toad caught from eight localities was triploid Did not find a single diploid or tetraploid Batura toad. Both males and females were found 3N female 3N male N elimination  elimination 2N 2N 2N   N   N 3N
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8 Sex in organisms Sex chromosomes and sex linkage:  In Drosophila, it is the number of X's that determine sex while in mammals it is the  presence or absence of a Y chromosome that determines sex.  Homogametic sex-  Producing gametes that contain one type of chromosome (females in  mammals and insects, males in birds and reptiles) Heterogametic sex-  Producing gametes that contain two types of chromosomes (males in  mammals and insects, females in birds and reptiles) Species XX XY XXY XO Drosophila female male female Male (sterile) Humans female male male female Bridges could tell genotype by where the sex chromosome went and therefore established  that chromosomes carried genes
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9 Non-sex chromosomes are called autosomes Humans have 22 autosomes, Drosophila has 3 Homogametic sex-  XX-  females in humans males in birds Heterogametic sex- XY- males in humans Hemizygous gene present in one copy in a diploid  organism Human males are hemizygous for  genes on the X-chromosome
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10 Sex linked Described below is an actual case history of the use of pedigree analysis: After the death of a wealthy individual (II:3), a man claiming to  be his son (III:3) filed a paternity suit and claimed the inheritance. 
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This note was uploaded on 09/15/2011 for the course BIO 105 taught by Professor Sullivan during the Winter '08 term at University of California, Santa Cruz.

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Lect3 - Bridges and Triploids White XwXwY XY Y YY Y lethal...

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