Download Mendelian Genetics

Mendelian Genetics
Gregor Mendel
• Father of genetics
(1880’s)
• Discovered how traits
were inherited
• Genetics = study of
heredity
• Heredity = the passing
of traits from parents to
offspring
Mendel’s Experiments
• Mendel did his study on
pea plants
• Pea plants have many
traits (tall/short, purple
flowers/white flowers)
• Pea plants can be selffertilized or
cross-fertilized
Mendel’s Experiments
Types of Plants
•True-Breeding - these
plants always create plants
that look like themselves
•Hybrids – offspring of
true-breeding plants
-EX: Tall x Short = hybrid
Dominant vs. Recessive
• Some traits are dominant over others
• Recessive traits are masked by dominant traits
• Tall (T) x Short (t) = all tall offspring (hybrids,
Tt)
Genes and Alleles
• Mendel discovered that each trait is controlled by two factors
• Allele = version of a gene
• Genes = factors that determine your traits
Explaining the Cross
• When a parent makes
sperm or eggs, their
genes separate
(PRINCIPLE OF
SEGREGATION)
• The GAMETES (egg or
sperm) contain either a
T allele (tall) or a t allele
(short)
Genotype and Phenotype
• GENOTYPE - genetic
make up/allele the
organism has (TT, Tt, tt)
• PHENOTYPE - physical
appearance of the gene
(tall or short)
Punnet Square
Monohybrid Cross – 1 trait
Punnet Square
Dihybrid Cross
= 2 traits