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Mendelian Genetics
→ Blending Theory of Inheritance → traits from parents mix evenly → HOWEVER, some traits that do
not appear in one generation could do so in the next one… no information is lost along the way
→ Fundamental Theory of Heredity - Gregor Mendel (experiment with flowers) → inheritance involved
the passing of genes[hereditary factors] from parents to the offspring [3 Laws of Inheritance]
→ → → Dominance & Recessiveness → one allele is always more dominant in a gene
→ → → Segregation → during gamete formation (meiosis) alleles for the same gene split (parental
gametes)

→ → → Assortment → genes on different chromosomes are not connected to each other and are
randomly distributed to sex cells independently of each other

→ Punnett Square → used to predict offspring genotype and phenotype probabilities
→ monohybrid cross → a cross between two individuals that involves one pair of contrasting trait
→ dihybrid cross → a cross between individuals involving two pairs of contrasting traits

B

b

brown

blond

B

BB

Bb

b

Bb

bb

Possible Genotypes
BB → ¼
bb → ¼
Bb → ½
Genotype Ratio
1 BB : Bb 2 : bb 1
Possible Phenotypes
Brown → ¾
Blond → ¼
Phenotype Ratio

3 Brown : Blond 1
→ testcross → the crossing of unknown genotype with a homozygous recessive one individual (bb) in
order to see whether the unknown genotype is Bb or BB
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