Chapter 9 - Chapter 9 Patterns of Inheritance Biology Society Dog Breeding o Genetics the scientific study of heredity Explains inborn traits and

Chapter 9 - Chapter 9 Patterns of Inheritance Biology...

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Chapter 9: Patterns of InheritanceBiology & Society: Dog BreedingoGenetics– the scientific study of heredityExplains inborn traits and patterns of bred dogsInbreeding serious genetic defects-Useful for vet / human medicine oRelationship b/w Genetic Makeup & BehaviorBehavior is influenced both by:-Genes-Environment / careoChapter PreviewBasic rules of how genetic traits are passed b/w generations-How behavior of chromosomes accounts for rulesInheritance patterns-How to predict ratios of offspring with particular traitsHERITABLE VARIATIONA ND PATTERNS OF INHERITANCEoHeredity– the transmission of traits from one generation to the nextGenetics– the scientific study of heredity-Discovered by Gregory Mendel (peas)oMendel’s StudiesPaper (1866) = parents pass “heritable factors” down to offspring-Responsible for inherited traitsHeritable factors (aka: genes) retain individual identifies generation after generation-Even if mixed up or temporarily maskedIn an Abbey GardenoSome TermsCharacter– a heritable feature that varies among individuals-Ex: flower color
Trait– a variant of a character (heritable gene)-Ex: purple or white flowersoWhy he chose pea plantsEasy to grow & many readily distinguishable varieties-Purple / white flowersCould control their reproduction-Self-fertilization by covering flower to ensure no external pollen got in his experiment-Pollinate by hand when cross-fertilizingTrue Breeding(purebred) – varieties for which self-fertilization produced offspring all identical to the parentCharacters used occurred in 2 distinct formsoCross-BreedingHybrids– the offspring of two different true-breeding (purebred) varietiesGenetic cross– the cross-fertilization of two different true-breeding (purebred) varieties-P generation– the parental plants-F1 generation– the hybrid offspring-F2 generation– the self-fertilization or fertilization offspring of F1 plantsMendel’s Law of SegregationMonohybrid CrossesoMonohybrid cross– a cross between parent plants that differ in only one characterEx: crossing purebred purple flower with purebred white flowerFindings in offspring-NO white flowersDOESN’T MEAN white flowers are gone forever-In F2, 3:1 purple to white flowers
-Color factors – some carry more than oneo4 Hypotheses:1. There are alternative versions of genes, the units that determine heritable traits-Alleles– the alternative versions of a geneEx: P for purple and p for white2. For each inherited character, an organism inherits two alleles, one from each parent-Inherited may be same or diff-Homozygous– an organism that has two identical alleles for a gene (homozygote)-Heterozygous– an organism that has two different alleles for a gene (heterozygote)3. If the two alleles of an inherited pair differ, then the dominant allele determines appearance & recessive has no affect on appearance-

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