The passing of genetic traits from parent to offspring Heredity The passing of genetic traits from parent to offspring

Gregor Mendel – Father of Genetics Austrian monk who studied patterns of inheritance in garden pea plants Mendel controlled which plants pollinated other plants

Test corrections due today!! What do you think the difference is between self-pollination and cross-pollination? Test corrections due today!!

Gregor Mendel – Father of Genetics Pollination in pea plants can either be: Self-Pollination (where pollen from 1 plant lands on the same plant) “True-Breeding” always produces offspring with traits that match the parent

Gregor Mendel – Father of Genetics 2. Cross-Pollination (where pollen from 1 plant lands on a different plant) Occurs naturally from wind, water, animals, and bees This method allowed Mendel to select what traits he could test

Mendel's Results First Generation Crosses Purple X Purple = Purple White X White = White Purple X White = Purple Why were there no white flowers or pink flowers?

Second Generation Crosses Mendel cross-pollinated 2 purple hybrid plants The trait that had disappeared in the 1st generation always reappeared in the 2nd generation

Pg. 450 Table 1 “Mendel’s Results” 705 purple / 224 white Ratio: 3.15:1 For every 3 purple flowers, there will roughly be 1 plant with white flowers Pg. 450 Table 1 “Mendel’s Results”

Mendel's Conclusion A genetic trait that is present is called a dominate trait “The Big Guy” A genetic trait that is not present and has “disappeared” is called a recessive trait “The Little Guy”

Traits and Inheritance Each parent gives one set of genes (instructions for an inherited trait) to offspring Offspring get 2 forms of the same gene for every characteristic – one from each parent These different forms (dominant and recessive) of a gene are alleles

Dominant allele = capital Recessive allele = lowercase Genes affect an organism’s physical appearance or phenotype Ex. flower color, seed texture Inherited alleles together form the genotype Dominant allele = capital Recessive allele = lowercase

An organism with 2 dominant or 2 recessive alleles is homozygous Ex. PP or pp An organism with 1 of each is heterozygous Ex. Pp

Punnett Squares Punnett square – chart where all possible gene combinations are shown in a cross of parents

Probability Probability is the likelihood that something will happen