MCB 181 1st Edition Lecture 24Outline of Previous Lecture I. Mendel and the Gene IdeaII. Mendel’s ConceptsIII. Clicker QuestionsOutline of Current Lecture I. Mendel’s Concepts (Continued)II. Extending Mendel’s RulesCurrent LectureI. Mendel’s Concepts (Continued)l. Dihybrids and Dihybird Crossa. Crossing two true-breeding parents differing in two traits produces dihybrids in the F1 generation that are heterozygous for both characteristicsb. A dihybrids cross, a cross between F1 dihybrids, can determine whether two characters are transmitted to offspring as a package or independentlyc. Law of Independent Assortment – states that each pair of alleles segregates independently of each other pair of alleles during gamete formationi. Strictly speaking, this law applies only to genes on different, non-homologous chromosomesd. Many heritable characters are not determined by only one gene with two alleles like seen with the pea plants, however, the basic principles of segregation and independent assortment apply even to more complex patterns of inheritancee. Meiosis is responsible for the principle of Independent Assortment:II. Extending Mendel’s Rulesa. By studying a simple genetic system, Mendel discovered the most fundamental rules of inheritanceb. Sex Chromosome and the X-Linked Inheritance: The genes found in the X-chromosome are called X-linage or sex-lined inheritance c. Linkage: The physical association of genes that are found on the same chromosome is called
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