Gregor Mendel Discovers The Principles of Inheritance. Lone Peak High School Biology 2002-03 By Brad Shuler. Who was Gregor Mendel? . Born in 1822 Studied science, mathematics and statistics Entered an Austrian monastery to be a monk Studied heredity in peas - PowerPoint PPT Presentation
Gregor Mendel Discovers The Principles of InheritanceLone Peak High School Biology 2002-03By Brad Shuler
Who was Gregor Mendel? Born in 1822Studied science, mathematics and statisticsEntered an Austrian monastery to be a monk Studied heredity in peasDiscovered the principles of heredity
Mendels ObservationsHe identified that pea plants have a variety of traits when observing the different characteristics of the plant.He developed pure strains of plants. (i.e. tall, short, green pod, yellow pod, wrinkled, round, etc.) These are often called purebreds.The purebred plants consistently produced offspring with the given trait. (i.e. tall always produced tall)
Mendels PeasThese are the seven characteristics, each having two contrasting traits, that Mendel identified.
Mendels ExperimentsHe experimentally crosses different strains of pure plants (parental generation) to develop hybrids (F1 generation).He then crossed these hybrids (F1 gen.) and analyzed the results (F2 gen.)
Mendels ResultsThe hybrids (F1 gen.) only displayed one of the parental traits. (tall)When crossing two hybrids, some of the resulting offspring (F2 gen.) displayed one of the parental traits and some displayed the other. (some tall some short)These traits in the F2 generation consistently occurred in a 3 to 1 ratio. (3 tall: 1short)
Mendels Conlusions:The Principle of SegregationEach plant has two factors (genes) for any given characteristic (length of stem, color of pod, shape of seed, etc.)They receive these factors from their parents.When a plant reproduces it only passes one of its two factors to its offspring. The factors are contained in the gametes, the egg or sperm.
Mendels Conlusions:The Principle of Dominance and RecessivenessFactors for certain traits seem to mask or hide the others when both are present in hybrids (Tt=tall).Factors that are that always displayed when present are called dominant.Factors that are hidden or masked by the dominant are called recessive.Recessive traits are only displayed in purebreds (i.e. short-tt, yellow pod-yy).