1. The Basis of Heredity

2. Principle of Dominance
Tracked seventraits through seven generations of garden
Peas.
First cross from parent – Parental Generation
The next cross – Filial Generation (FG1, FG2, FG3, FG4
FG5, FG6, FG7)
Garden peas reproduce through self-pollination.
This creates a pure copy of the plant, so that when
Mendel wanted to isolate a trait, he could cross-
pollinate and be sure that what he was observing was
the isolated trait.
Gregor Mendel
Principle of Dominance

3. Offspring of cross-pollinated plants – Progeny
Dominant Trait – when the combination of genes predominantly produces a specific characteristic (round seed)
Recessive Trait – low probability of a trait developing (wrinkled seed)
Allele – Alternate form of gene
gene for seed colour – 2 alleles (1 for round and one for wrinkled)
Dominant Allele – R Recessive Allele – r
Two copies of a gene in a gene pair undergo Segregation during the formation of the sex cells.

4. Mendel’s Principle of Segregation
Mendel cross-pollinated the parent plant to determine the seed (F1). Allowed that plant to grow and self-pollinate to observe transmission of trait to F2 generation
F2 generation has a 3:1 ration (75% dominant, 25% recessive)
Both alleles are the same – Homozygous
Alleles are different – Heterozygous
Complement of gene is Genotype, Physical expression is Phenotype
Mendel’s Principle of Segregation

6. Homozygous – each gamete carries the same allele
Heterozygous – each gamete could receive either allele