01:119:115 Lecture Notes - Lecture 62: Gamete, Dihybrid Cross, Chromosome
5 Apr 2016
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Document Summary
Prevailing the idea at the time blending inheritance . Characters are determined by heritable factors (gene) passed generation to generation. Factor from one of parents can mask expression of factor from other parent. Mendel developed a hypothesis to explain the 3:1 inheritance pattern in f2 offspring. 4 related concepts make up this model: alleles: alternative versions of genes, alleles inherited; 1 from each parent, dominant and recessive alleles, law of segregation. Gene for flower color exists in 2 versions: purple and white. Each gene is at same locus on homologous chromosomes. Concept #2; 2 alleles inherited; 1 from each parent. Mendel made this deduction without knowing about chromosomes. May be identical as in the true breeding plants (p generation) Or may be different as in the f1 hybrids. If the two alleles at a locus are different, then: The recessive allele has no effect on appearance. Ex- in flower-color f1 plants: purple flowers because purple allele is dominant.
