Post on 17-Jan-2016
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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
F1= First Filial (offspring), F2= 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