mendelian genetics 1. gregor mendel (1822-1884) father of genetics austrian monk between 1856 –...

Download Mendelian Genetics 1. Gregor Mendel (1822-1884) Father of genetics Austrian Monk Between 1856 – 1863 he studied ~28,000 pea plants Importance of his work

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Mendelian Genetics

Mendelian Genetics

1Gregor Mendel(1822-1884)Father of geneticsAustrian MonkBetween 1856 1863 he studied ~28,000 pea plantsImportance of his work not realized until 20th century, ~20 years after death

2Mendels Experiments3

The PeasAdvantages of Pea Plants:Grown in small areasdistinct heritable features Each feature has two variantsLots of offspringCan self-fertilize or cross fertilize

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Reproduction in Flowering PlantsPollen (produced by stamen) contain sperm Ovary contains eggPollen grows tube down style to carry sperm to eggSelf-fertilization - sperm and egg from same flowerCross-fertilization - sperm and egg from different flower

5His ExperimentsFirst created true-breeding peas by allowing them to self-fertilize True breeding = only produces offspring with one specific trait6

His ExperimentsThen, he cross-fertilize (hybridized) two contrasting, true-breeding varieties (P1 generation - parent)Offspring is the F1 Generation first filialThen allowed the F1 hybrids to self-pollinate to produce an F2 generation 2nd filial

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His Experiments8

P1 GenerationF1 GenerationAll tallF1 GenerationF2Generation3 tall, one shortHis Experiments

9Results:F1 generation: all dominant phenotypesF2 generation: 3:1 ratio of dominant to recessive phenotypesHis ExperimentsCreated three Laws of InheritanceLaw of DominanceLaw of SegregationLaw of Independent Assortment

10Mendels Laws of Inheritance11

Law of DominanceIn a cross of true-breeding parents, only one form of the trait will appear in the next generationThe apparent trait is dominant, the other is recessive12Law of SegregationThe pair of factors (alleles) is segregated, or separated, during formation of gametes (sperm and egg)

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Law of Independent AssortmentFactors (alleles) for different traits are distributed in gametes independently of each other

14Applying Mendels Laws Punnet SquaresTwo types used to show expected genotype of offspringMonohybrid2 gametes from each parent2x2 gridDihybrid4 gametes from each parents4x4 grid

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Applying Mendels Laws Test CrossA mating between an organism with unknown genotype and a homozygous recessive organismExample:Mice can either be brown (B) or white (b). You have a mouse with a brown coat. Can be BB or BbIf Bb: offspring half brown/half whiteIf BB: offspring all brown16

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