Download Figure 14.0 Painting of Mendel

Genetics
Gregor Mendel: Father of Genetics

Genetics: study of
heredity

Heredity: passing
traits from parent to
offspring

Used peas to study
heredity
Why Peas?



1. Several Traits
2. Control mating
3. Small, grow easily, and matures
quickly
Alleles: Different versions of a gene
Ex: White and Purple Flowers
Mendel’s Experiment

Monohybrid Cross: One pair of contrasting
traits.


Ex: Mating a plant with purple flowers with white
flowers
True-breeding: All offspring would have
only one form of the trait

Ex: Purple-flowering plant only has purpleflowered offspring
Mendel’s Experiments
Vocabulary

Dominant: Expressed in appearance (A)

Recessive: Not noticeable in appearance (a)

Homozygous: AA or aa

Heterozygous: Aa
More Vocabulary

Genotype: Genetic make up (ex: Pp)

Phenotype: Appearance (ex: Purple flowers)
Laws of Heredity

Law of Segregation

The two alleles for a trait separate when gametes are
formed

Law of Independent Assortment

Alleles of different genes separate independently of
each other during meiosis
Law of Segregation

Separation of alleles into
separate gametes

50% chance that one
allele will go into a
gamete
Law of Independent Assortment
Punnett Square
Ratios
Test Cross
Dihybrid Cross: Cross that involve two traits