9 1866- published findings on plant breeding and inheritance Gregor Mendel“Father of Genetics”1866- published findings on plant breeding and inheritance(During American Civil War)Not discovered until early 1900s
10 Keys to Success Used “True-Breeding” pea plants (“purebreds”) Always produce offspring with only one form of a traitStudied only 1 characteristic at a timeAnalyzed data mathematically
11 Pea Plant Reproduction Self-pollinationPollen fertilizes egg cells on same flower1 parentCross-pollinationPollen from flower of one plant fertilizes egg cells on another plant2 parents
12 Mendel controlled breeding by cross-pollinating To prevent self-pollination, Mendel removed male parts from a flower and dusted the flower with pollen from a different pea plant
13 Genetics:The science of heredityHeredity:The biological inheritance of traits from parent to offspring
14 Genetics used for:Preventing & treating diseasesDeveloping tougher plants to increase food production
15 Generations F1 generation F2 generation P generation: parent generation“true - breeding”F1 generationFirst generation of offspringF2 generationSecond generation produced when f1 generations are crossed
16 AlleleThe different forms of a gene2, 3, or even 12 possible alleles per gene
17 DominantForm of the gene that is expressedCapital letter: T
18 RecessiveForm of a gene (allele) that is only expressed in homozygous stateLowercase letter: t
19 Homozygous2 identical alleles for the same traitHomozygous dominant: TTHomozygous recessive: tt
20 Heterozygous2 different alleles for the same traitTt : dominant trait will be expressedAlso called a “hybrid”
21 GenotypeGenetic make-up of an organismThe “letters”Tt or TT or ttAa or AA or aa
22 PhenotypePhysical expression of a traitEx: Tall or Short
26 Seed Color P generation cross: (“true - breeding”) Yellow peas x Green peasF1 generation:All yellowF2 generation:6022 yellow : 2001 green3 yellow : 1 green
27 Monohybrid cross Use a Punnett square to cross 2 hybrids: Yy x Yy What are the possible genotypes?What is the genotypic ratio?What is the phenotypic ratio?
28 Law of Independent Assortment Genes on separate chromosomes sort independently during meiosisAlleles for seed shape separate independently from seed color allelesSo, seed shape is not connected to seed color
29 Dihybrid cross A Special type of two - factor cross YyRr x YyRr (heterozygous for both traits)You will always find the same phenotypic ratio. What is this ratio?
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