Genetics

Genetics and Mendel! Mendel (b. 1822) in Czech Republic, moved to Vienna, Austria Worked as a monk and a HS teacher, gardened in spare time…. Little did he know his work would be the foundation of modern genetics Genetics: the scientific study of heredity—the core of biology!

Vocabulary Fertilization: The process were male and female GAMETES unite. True breeding: Self-fertilization, it occurs when male gamete within a flower combines with a female gamete in the same flower.

Cross pollination: Pollen from one flower fertilizes a second different flower. Trait: A specific CHARACTERISTIC that varies for one INDIVIDUAL to another.

Generations F 1 = First Filial (offspring), F 2 = Second Filial

Vocabulary Hybrid: The offspring of crosses between parents with different TRAITS. Genes: A sequence of DNA that codes for a protein and thus determines a trait. Alleles: Different forms of a TRAIT.

Mendel’s Conclusions Biological inheritance is determined by TRAITS that are passed from one generation to the next. Today we call Mendel’s factors: Traits=Genes, Form= Allele Every trait is controlled by one GENE that occurs in 2 contrasting forms called ALLELES.

Principle of Dominance Some alleles are DOMINANT and some are RECESSIVE An organism with a dominant allele for a trait will ALWAYS exhibit that form of the trait. An organism with a recessive allele for a trait will exhibit that form only if the dominant allele is NOT present.

Segregation Medel’s question, “Did the recessive alleles disappear?”

Principle of Segregation Segregation = Separation The separation of alleles occurs during the process of MEIOSIS when gametes are formed. Each gamete carries a single copy of each gene.

Vocabulary Homozygous: two identical alleles (TT) or (tt) Heterozygous: two different alleles (Tt) Phenotype: physical or outward appearance (ex: tall, short, yellow, green) Genotype: genetic makeup (TT, Tt, Gg, gg)

In Short… Capital Letters (T) = Dominant Trait Lowercase Letters (t) = Recessive Trait T= Tall and t= short Homozygous: Having 2 IDENTICAL alleles for a trait. (TT) or (tt) Heterozygous: Having 2 DIFFERENT alleles for a trait. (Tt)

Prediction Uses Probability, not magic! Probability- likelihood a particular event will occur We can study Mendel’s crosses with Punnett Squares (diagram that shows gene combinations from a genetic cross) Used to predict and compare the genetic variations that can occur

How Punnett Squares Work