2 What we already know…“Inheritable factors” or genes are responsible for all heritable characteristicsPhenotype is based on GenotypeEach trait is based on two genes, one from the mother and the other from the fatherTrue-breeding individuals are homozygous (both alleles are the same)
3 Mendel’s Laws: Unit Factors The appearance of each plant was determined by two “inheritance factors”Each organism has two alleles for each trait
4 Mendel’s Laws: Rule of Dominance “Inheritance factors” can be either dominant or recessiveObserved traits are dominant, traits that disappear are recessiveHomozygous Dominant (TT): two dominant alleles, shows dominant traitHomozygous Recessive (tt): two recessive alleles, shows recessive traitHeterozygous (Tt): has one dominant allele and one recessive allele, shows dominant trait
5 Mendel’s Laws: Law of Segregation “Inheritance factors” separate randomly when sex cells are formedThis means each parent can only pass on ONE copy of their two genes to each offspringThis is RANDOM, like the flip of a coin
6 Mendel’s Laws: Law of Independent Assortment “Inheritance factors” for different traits are passed from parents to their offspring independently of one anotherGenes for different traits are inherited independently of each other…Genes for different traits are often on different chromosomes, which separate according to the law of segregation when gametes are formed
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