BIOL 3333 1st Edition Lecture 2GeneticsPre Mendelian Concepts of Inheritance: Charles Darwin: his views of inheritance not dramatically different than ancient greeks- “gemules” derived from individual body parts- transported to sex organs- on fertilization are blended in the progeny- concept of continuous variationMendel: 1854: began experiments with the common garden pea at Abbey of St. Thomas The Common Garden Pea: - Male and female reproductive organs contained in same flower - makes self fertilization easySummary of Mendel’s Protocol: - Characteristics are NOT blended - apparently inherited as discrete and particulate entities- constructed a model (hypothesis) which explained above data sets*True breeding plants carried a double information set for same traitInformation separates (segregates) on gamete cell formationSame P - double information set restored on fertilizationHomozygote: 2 copies of same factor Heterozygote: two DIFFERENT factorsPrinciples of Inheritance (Mendel)- Unit Inheritance - factors are discrete and particulate entities - they are not mixed or diluted during inheritance- Principle of Segregation: the paired factors segregate (separate) from each other during the formation of gametes- Principle of Independent Assortment: parental factors segregate at random- if 2 sets of factors are followed in the same crosss, each gene pair segregates independently of the other (you see 2 independent 3:1 ratios for each trait in a dihybrid cross) These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Terminology Review: - inherited factors (A or a) are termed GENES- alternate forms of a given gene are termed ALLELES- AA or aa = homozygous- Aa = heterozygous- Genotype = the actual gene complement of an individual, usually with regard to homozygosity or heterozygosity for a given gene pair- Phenotype = the physical expression of the genotype- Locus = the specific site on a chromosome where a gene is
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