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Bio 120 notes - Bio Ch 14 Peas available in...

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Bio Ch. 14 Peas available in varieties(purple, white), can control which plant mates with which Reproductive organs of pea plant in flowers Pea plants usually self-fertilize- pollen from stamen land on carpel(egg bearing organ) of same flower. Sperm from pollen fertilizes egg in carpel Cross-pollination(2 diff flowers) –remove immature stamens of plant before produce pollen, and dust pollen from another plant onto altered flower. Hybridization-mating of 2 true breeding plants(all purple or white) P generation-parental, F1, F2- leads principles of hereditary Law of Segregation- 2 alleles for heritable character separate during gamete formation and end up in different gametes. If true breeding(same alleles) then allele present in all gametes If diff alleles, half gametes get dominant allele and half recessive -F1 plants all purple, but when self pollinate, F2 plants have some white flowers-3:1 -Only purple flower factor affect flower color in these hybrids *Allele- Alternative versions of a gene(purple, round) – Creates variation in inherited characters *For each character, an organism inherits 2 alleles, one from each parent *If the 2 alleles at a locus(color) differ, then dominant allele determines organisms appearance and recessive has no affect Phenotype-traits(color) Genotype –genetic makeup(Pp, pp) Testcross- to determine organisms genotype – breed recessive homozygote with organism of dominant phenotype, but unknown genotype *Law of Independent assortment- each pair of alleles segregated independently of other pairs of alleles during gamete formation. 9:3:3:1 Dominance depends on which phenotypic trait is considered Pleiotropy-single gene affects several phenotypic characters Polygenic inheritance- additive effect of two or more genes on a single phenotypic character. Ch. 15.1-15.3 Chromosome-gene pairs in diploid cells, meiosis-homologous chromosomes separate and alleles segregate, fertilization restores chrom-gene pairs. Chromosome theory of inheritance- genes have specific loci(positions) on chromosomes, and chromosomes undergo segregation and independent assortment. homologous-segregation of alleles to diff gametes nonhomologous- independent assortment of alleles for two or more genes on diff chromosomes. Fruit fly- hundreds of offspring can be bred every 2 weeks, only 4 easily distinguishable chromosomes(3 autosomes, 1 sex) female xx, male- xy Wild type- normal red eye(w+) Mutant phenotype- white eye(w) Specific gene carried on specific chromosome(eye color gene on X chromosome) -female could only have white eye only if both X chromes carry recessive mutant allele(impossible-all F1 fathers had red eyes) Linkage Each chromosome has hundreds of genes Linked genes-genes on same chromosome
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Body color and wing size genes partially linked genetically(located on same chromosome) Independent assortment of chromosomes (during meiosis) Offspring have traits that no match parents.
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