Genetics

The scientific study of heredity Heredity is the passing on of traits from parent to offspring

Generations P generation –Parental generation F1 generation –First filial F2 generation –Second filial

Hybrids Offspring of parents with different traits

Traits Trait: specific characteristic that varies from one individual to another

Gregor Mendel Austrian monk Born in 1822 in what is now the Czech Republic Took care of the monastery garden

Gregor Mendel Studied pea plants Fertilization: male and female reproductive cells join –Produces a new cell which is the offspring

Mendel’s Experiments Mendel’s pea plants: –Called True-Breeding plants –Self-pollinate Pollen from the plant would fertilize it’s own flower

Mendel’s Experiments If they were to self-pollinate, the new plants would look exactly like the parent plant

Mendel’s Experiments Cross pollinated peas in order to see different characteristics

Cross Pollination Take pollen from one plant and fertilize a different plant Caused different characteristics to come out in the new plants

Mendel’s Experiments Mendel’s Peas: –Cross pollinated peas with different traits to see what the offspring would look like

Mendel’s Experiments Mendel looked at traits: –Seed color –Seed shape –Pod color –Height

Genes and Dominance Mendel’s First Conclusion: –Biological inheritance is determined by factors that are passed from one generation to the next These factors are called genes

Genes and Dominance Genes: chemical factors that determine traits –Genes have many forms –Alleles: different forms of genes Example: yellow seed and green seed

Genes and Dominance Mendel’s Second Conclusion –Some alleles are dominant and some are recessive This is called the Principle of Dominance

Principle of Dominance If an individual has a dominant allele for a particular trait, that trait will always be seen If the individual has the recessive form, the trait will sometimes be seen (if the dominant gene is not present)

Segregation Mendel wanted to answer: Did the recessive gene disappear or was it still present? –Allowed the F1 generation to produce an F2 generation Crossed some F1 plants in order to see the offspring

F1 Cross The recessive traits re-appeared in the F2 generation! –In the F1 generation, the dominant allele hid the recessive allele causing only the dominant trait to be seen

Segregation Segregation: separation of the alleles –Occurs during gamete production –Gamete: sex cells When each F1 plant flowers and produces gametes, the two alleles segregate so that each gamete has only one copy of each gene