Genetics Genetics and Mendel Mendel b 1822 in
Genetics
Genetics and Mendel! Mendel (b. 1822) in Czech Republic, moved to Vienna, Austria n Worked as a monk and a HS teacher, gardened in spare time…. n Little did he know his work would be the foundation of modern genetics n Genetics: the scientific study of heredity—the core of biology! n
Vocabulary Fertilization: The process were male and female GAMETES unite. n True breeding: Self-fertilization, it occurs when male gamete within a flower combines with a female gamete in the same flower. n
n Cross pollination: Pollen from one flower fertilizes a second different flower. n 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. n Genes: A sequence of DNA that codes for a protein and thus determines a trait. n Alleles: Different forms of a TRAIT. n
Mendel’s Conclusions n n n 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 n An organism with a dominant allele for a trait will ALWAYS exhibit that form of the trait. n An organism with a recessive allele for a trait will exhibit that form only if the dominant allele is NOT present. n
Segregation n Medel’s question, “Did the recessive alleles disappear? ”
Principle of Segregation n Segregation = Separation n 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) n Heterozygous: two different alleles (Tt) n Phenotype: physical or outward appearance (ex: tall, short, yellow, green) n Genotype: genetic makeup (TT, Tt, Gg, gg) n
In Short… Capital Letters (T) = Dominant Trait n Lowercase Letters (t) = Recessive Trait n T= Tall and t= short n Homozygous: Having 2 IDENTICAL alleles for a trait. (TT) or (tt) n Heterozygous: Having 2 DIFFERENT alleles for a trait. (Tt) n
Prediction Uses Probability, not magic! Probability- likelihood a particular event will occur n We can study Mendel’s crosses with n Punnett Squares (diagram that shows gene combinations from a genetic cross) n Used to predict and compare the genetic variations that can occur
How Punnett Squares Work
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