BIO 15B NOTES - Bio 15B February 11, 2008 True Breeding:...

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Bio 15B February 11, 2008 True Breeding: -Experiments with pea plants. -Pollen contained sperm; cut stamens of male (white) plant so that it can’t self fertilize and transferred pollen from stamens to carpel of purple plants. -Purple and white flowering pea plants crossed. Monohybrid Cross (1 trait): - True-breeding : Parents: Purple x White - F1 Generation : All came out as Purple flowers. o Fertilization of F1 generation among themselves - F2 Generation : ¾ are Purple and ¼ are White Results : - There are alternative forms of genes (alleles) - An organism gets one allele from each parents - The alleles separate when gametes form and recombine at fertilization - Alleles can be dominant or recessive Principle of Segregation : organisms have pairs of genes that segregate during gamete formation and come together during fertilization. ~the 2 genes segregated from one another; gametes when fertilized never end up with the 2 gene mixed together; their separated Punett Square: B b B BB Bb B Bb Bb Phenotypic Ratio 1 BB: 2 Bb: 1bb B- Dominant b- Recessive Homozygous- Homozygous (same) Phenotype: Looks; what you see. Genotype: Genetic makeup Gene: allele Dihybrid Cross (2 traits): - P Generation : Round seed (dominant) ( R) / Yellow seed (dominant) ( Y ) x Wrinkled seed (recessive)/ Green seed (recessive) - F1 Generation : RrYy - F2 Generation : 4 possible outcomes: 9/16 yellow round; 3/16 green round; 3/16 yellow wrinkled; 1/16 green wrinkled Principle of Independent Assortment : Each pair of alleles segregates independently during gamete formation.
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~gametes can end up mixed/in different combinations (like the parents) or separated characteristics Huntington’s Disease: disease forming allele form clumps in nerves cells killing them. Only need to inherited one allele in order to have to protein killing allele. Carrier Recognition: - Family history of recessive disorder - Is individual NN or Nn (carrier)? - Pedigree analysis, biochemical tests, DNA tests. February 13, 2008 Exception to Principle Individual Assortment with fruit flies: (female-gray body, long wings [wild-type]) (male-black body, short wings) GgLl x ggll [Can put together/ 4 possibilities: GL, gl, Gl, gL] GL gl Gl gL Gl GgLl Gray/ Long 1 ggll Black/ short 1 Ggll Gray/ short 1 ggLl Black/ long 1 - however our prediction compared to the experiments did not come out with same results. . - gray/ short and black/ long represent 17% recombinant Gametes (this tells us how close together genes are to one another; if they are close together there is unlikely a cross over to occur between them, but if they are separated than there can be a cross over. Tetrad [GL and gl]-> Crossing over-> 1. Parental Gametes [GL and gl] and 2. Recombinant Gametes [Gl, gL, gl]
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This note was uploaded on 05/02/2008 for the course BIOL 15b taught by Professor Neil during the Spring '08 term at Brandeis.

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BIO 15B NOTES - Bio 15B February 11, 2008 True Breeding:...

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