Unit3_notes - Unit Three Notes Heredity The transmission of...

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Unit Three Notes Heredity The transmission of traits from one generation to the next. Greg Mendel –Austrian Monk---1800’s Observed some traits disappeared in one generation, only to reappear in the next. Hypothesis Some traits are stronger than others. Experimental Design Needed something which could be easily manipulated. Something with a variety of visible characteristics. The Garden Pea Quick generation time Does not require much space Peas undergo self-fertilization o Pollinate themselves Could also pry open petal to make specific crosses between plants. Many visible traits: Flower color Seed color Seed shape Plant height Parental Generation o For each trait studied he wanted a true breeding plant to begin the experiment. o True Breeding Generation after generation breeds true to a single visible trait. Experiment o Cross two different parental generation plants (each One displays O ne version of the trait) o Parental white flower x purple flower cross them and plant the seeds to get the first generation
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o F1—First Filial (Latin for son/daughter) all purple 100%.
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Recorded The Numbers & Traits Of All Generations o Allowed F1 to self-fertilize. o Counted the F2 for number of each trait. o 75% purple, 25% white. Dominant— Trait which was solely visible in F1 generation. Recessive— Trait which disappeared in F1 reappeared in F2. Allowed F2 to self-fertilize. o F2 white only produced white. o Recessive individuals always bred true. o F2 purple o Progeny a mix of Purple individuals & white individuals. Mendel’s Theory o Individuals possess two copies of ea. trait factor (called genes). o The two trait factors may be identical to each other or not. Homozygous o The two trait factors in an individual are identical for a specific trait. Heterozygous o The two trait factors are different for a specific trait. Mendelian Notation o Each trait designated by a single letter. o Dominant version upper case. o Recessive version lower case. Alleles - alternate forms of particular trait Trait Alleles Notation Flower color White Purple p P Plant Height Tall Short T t Seed Shape Round Wrinkled R r Genotype: Sum of all alleles of an individual. o Homozygous / Heterozygous RR or rr Rr Phenotype: Physical Representation of genotype, What we see o PP Purple o Pp Purple o Dominance Relationship is important in the heterozygote
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o Allows prediction of progeny genotypes based upon parental genotypes. o Determine all gamete possibilities of both parents. o Write one parental set of gametes across the Horizontal axis, write the other parental set of gametes down the vertical axis of the Punnett Square. One Factor Cross RR x rr Determine possible gametes for each parent Write one parent along the side the other across the top. Off Spring Genotypes In
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This note was uploaded on 01/16/2012 for the course COURSE 1000 taught by Professor Staff during the Fall '10 term at Temple.

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Unit3_notes - Unit Three Notes Heredity The transmission of...

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