Gregor Mandel – Heredity laws
Genes: parts of chromosomes that govern a trait, makes proteins that defines traits
Allele: alternate form of a gene. E.g. Gene for height, allele for tall or short
Genotype: actual genetic information and what it says
Phenotype: the way the trait looks e.g. blue eyes
Sperm cell with a blue eye allele (a) on homologous chromosome 5 and egg cell with brown eye
allele (A) to make Genotype Aa, and phenotype brown eyes.
Dominate Trait: characteristic that is always used
Recessive Trait: Present but not used unless it’s the only allele
-One type of trait will be dominant and will trump the others.
Homozygous Dominant: AA or aa (both the same)
Homozygous Recessive: Aa (not the same)
P Generation: parent generation all with homozygous genes
F1 Generation: offspring from the cross of P generation, first filial generation
Law of segregation: states that the inherited traits are determined by pairs of alleles and
genes which Mandel called “factors”. These “factors” segregate (separate) in the gametes it
one in each gamete.
Law of independent assortment: States that the inheritance of one trait doesn’t affect the
inheritance of alleles for another trait
-Alleles pairs are passed to the offspring independently of each other
-One trait doesn’t affect the inheritance of another. Inheriting blue eyes has nothing to do
with inheriting blond hair.
-Does it with one trait at a time.
-Demonstrates how dominance and recessive genes could be passed onto from one
generation to another.
-Dominance Genotypes are indicated with a capital letter and letter represents the
-Recessive Genotypes are indicated with a lower case letter P1 Generation: BB bb
F1 Generation: Bb Bb Bb Bb
F2 Generation: BB Bb Bb bb