1. Mendel’s Laws

2. What we already know…
“Inheritable factors” or genes are responsible for all heritable characteristics
Phenotype is based on Genotype
Each trait is based on two genes, one from the mother and the other from the father
True-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 recessive
Observed traits are dominant, traits that disappear are recessive
Homozygous Dominant (TT): two dominant alleles, shows dominant trait
Homozygous Recessive (tt): two recessive alleles, shows recessive trait
Heterozygous (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 formed
This means each parent can only pass on ONE copy of their two genes to each offspring
This 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 another
Genes 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