BIOB 375 1st Edition Lecture 20 Outline of Last Lecture II. Chromosome Rearrangementa. Duplicationb. Deletionc. Inversiond. TranslocationOutline of Current Lecture III. Changes in chromosome numbera. Aneuploidy Current LectureChanges in chromosome number- AneuploidyHow to describe the genomes of an organism? a genome formulaX: represents basic chromosome number- Basic chromosome number is the number of chromosomes in a set of diploid genomeHumans are diploid species- Have 2 sets of chromosomes- Have 2 sets of genomes - Basic number of chromosomes in humans: X=23A genome formula2n: represents somatic cells or germ cellsn: represents gametesAneuploidy: the loss or gain of one or more individual chromosomes in the genome of a speciesHow was an aneuploid arisen?- Nondisjunction during meiosis I- Nondisjunction during meiosis II- Due to Robertsonian translocationTypes of aneuploidy:- Normal- Monosomy- Nullisomy- Trisomy- Monosomic addition - Tetrasomy- Disomic additionEffects of aneuploidy- Gametes produced by nondisjunction mainly pass through femalePolyploidy: the presence of more than two sets of chromosomes- Autopolyploidy: The extra set of chromosomes are from the same species- Allopolyploidy: The extra sets of chromosomes are from different
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