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