1. Genetics
Genetics = science of heredity, or how we inherit traits from our parents

2. How genetics began
1866 Gregor Mendel (a monk and plant breeder) published his findings on the method of inheritance
Passing of traits on to the next generation = heredity
He was successful because of the plants he worked with
Pea plants – true breeding plants
only produce offspring with one form of a trait
Mendel became known as the ”Father of Genetics”
Discovered 3 Laws of genetics

3. Inheritance of traits F2 generation had yellow and a few green seeds!!
Mendel noticed that certain varieties of the pea plant produced green seeds and other produced yellow seeds
To understand inheritance – Mendel ‘cross-pollinated’ the pea plants
Green seeds (y) with yellow seeds (Y) – P (parent) generation
What did he find?
Offspring of P Generation were all yellow
F1 generation
What happened to green seeds?
Planted F1 generation seeds
F2 generation had yellow and a few green seeds!!
Decided there must be two forms of genes on the plants = alleles

5. Dominant vs. Recessive traits
Dominant allele = the trait that is always seen when it is present
always capital letter
Heterozygous or Homozygous
Recessive allele = trait that is only seen when it is doubled
always lower case letter
only homozygous
can be hidden
Yellow seed color is dominant
Green Seed color is recessive

6. Genotype vs. Phenotype
Outward appearance does not always show the genes present in an organism
Phenotype = what something looks like
Color, height, weight, shape, smell
Genotype = allele pairs
Homozygous or heterozygous
YY or Yy

7. Mendel’s 3 Laws
Law of Dominance: dominant traits are expressed over recessive traits
Yellow colors were seen over the green colors
Law of Segregation: alleles for each trait are separated during meiosis then reunite during fertilization
YY separates so each new daughter cell gets the Y allele
Law of Independent Assortment: alleles are distributed randomly during the formation of gametes
Specific chromosomes have alleles on them – they are not all related

8. Punnett Squares
Allow us to predict the offspring of a cross between two known genotypes
Hybrid – heterozygous organism
2 types
Mono-hybrid cross
Hybrids of a single trait are crossed
Only looking at the patterns of color
Di-Hybrid Cross
More difficult than mono-hybrid crosses
Hybrids of multiple traits
Color and size

10. Father is heterozygous dominant for brown hair
Mother is homozygous recessive for blonde hair
Create a Punnett square to show their offspring