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Genetics. Chapters 11-12. True-breeding Hybridization P generation F 1 generation F 2 generation Alleles Dominant Recessive Homozygous Heterozygous (hybrid). Vocabulary. Law of segregation Law of independent assortment. Laws. http://www.bozemanscience.com/probability-in-genetics.
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Genetics Chapters 11-12
True-breeding • Hybridization • P generation • F1 generation • F2 generation • Alleles • Dominant • Recessive • Homozygous • Heterozygous (hybrid) Vocabulary
Law of segregation • Law of independent assortment Laws
http://www.bozemanscience.com/probability-in-genetics Laws of probability
Complete dominance • Incomplete dominance • Codominance Degrees of dominance
Maybe dominant at organismal level, but codominant at molecular level • Ex. Tay Sachs Dominance and Phenotype
Blood types Multiple alleles
Genes may have multiple phenotypic effects • Ex. Sickle cells, cystic fibrosis Pleiotropy
A gene at one locus affects a gene at another locus • Ex. Labrador retrievers p 217 Epistasis
Many genes involved • Ex. Human skin color and height Polygenic inheritance
Multifactorial-may include genetic and environmental factors • Ex. Heart disease, diabetes, cancer, alcholism, mental illnesses Nature and Nuture
To wed a cousin or not to wed, that is the question… consanguineous
Albinism • Cystic fibrosis 1/2500 of European descent (4% are carriers) • Sickle Cell Anemia (1/400) (2 allelesfull blown, but organismal level-incompletely dominant; heterozygotes have sickle trait-but may have trouble when oxygen low; molecularcodominant) Recessive disorders
Huntington’s Choreahttp://www.youtube.com/watch?v=Nt2WbFC9ybs • Achondroplasia Dominant Disorders
Sutton, Boveri, et.al • Mendelian genes have specific loci along chromosomes, and it is the chromosomes that undergo segregation and independent assortment Chromosome theory of Inheritance
Fly guy-Drosophila melanogaster • Great experimental organism • Small, large # of offspring, short life span, 8 chromosomes, easily observed traits Phenotype most commonly observed in natural populations~wild type; alternatives~mutant phenotypes Invented notation – use letter of first mutant discovered and wild is indicated with + So, red eyes are dominant and the wild type: w+ White eyes were first mutant: w Thomas Hunt Morgan
SRY-sex determining region of the Y • Y-linked • X-linked Sex chromosomes
Males can’t be carriers • Males get it from Mom • Males have it more often • Color blindness • Hemophilia-Royal disease (Queen Victoria) • Duchenne muscular dystrophy Sex Linked disorders
One of the X chromosomes is inactivated in embryonic development • Barr Body (Mary Lyon found it is random)-leads to a mosaic • Tortoiseshell cat X inactivation in Female Mammals
Attach methyl groups to DNA • On one X, XIST (X-inactive specific transcript) becomes activemakes RNA product that attaches to one andBarr body How X is inactivated
http://www.youtube.com/watch?v=-_UcDhzjOio Linked genes
Abnormal chromosome number • Nondisjunction in anaphase I or II • Monosomy • Trisomy • Polyploid • Down syndrome • Klinefelter • Turner Aneuploidy
Deletion • Duplication • Inversion • Translocation Alterations in chromosome structure
Cri du chat deletion of part of #5 • CML- chronic myelogenous leukemia reciprocaltranslocation between #9 and #22-shortened 22Philadelphia chromosome Disorders
Angelmans syndrome http://www.angelman.org/understanding-as/diagnosis/ • Prader-Willi’s syndromehttp://www.youtube.com/watch?v=-6nzi5Rc4wY Genomic imprinting