Bio for non majors 8

Bio for non majors 8 - • Downsyndrome is caused by...

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Modes of disease inheritance Autosomal Dominant Disorders A single faulty allele can cause damage even when there is a second functional allele Autosomal Recessive Disorders A single faulty allele is NOT sufficient to cause damage. Heterozygous individuals are carriers X-linked Disorders Disorders controlled by genes on the X chromosome Autosomal Dominant Disorder Example: Huntington disease Autosomal Recessive Disorder Example: Sickle-cell anemia X-linked Disorder Example: color-blindness Pedigrees Polyploidy One or more entire sets of chromosomes have been added to the genome of a diploid organism Causes: More than one sperm can occasionally fuse with an egg Non-disjunction during meiosis (1 gamete ends up with 2 sets of chromosomes) Aneuploidy Too many or too few of a single chromosome than normally exists in its species full set Often aneuploidy results in miscarriage
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Unformatted text preview: • Downsyndrome is caused by aneuploidy (3 of chromosome 21) • Causes: – Non-disjunction during meiosis – Also occurs in cancer cells during mitosis • Non-disjunction during meiosis Structural Aberrations in Chromosomes • Deletion – a chromosome fragment breaks off and does not rejoin any chromosome • Inversion – a chromosome fragment breaks off and rejoins the same chromosome, but in the inverted orientation • Translocation – non-homologous chromosomes exchange peices • Duplication – unequal crossing over results in a chromosome with a region duplicated Key Points • Autosomal Dominant, Autosomal Recessive, and X-linked disorders have unique patterns of inheritance • Non-disjunction during meiosis can be one cause of Polyploidy or Anuploidy • Aberrations can also occur within a given chromosome...
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Bio for non majors 8 - • Downsyndrome is caused by...

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