Genetics: Chapter 3 of Green book- cells and heredity
GENETICS – The study of heredity. Heredity – the passing of physical characteristics from parents to offspring. Each characteristics is called a trait.
What determines our traits? Genes – the factors that control traits. The different forms of genes are called alleles An organism’s traits are controlled by the alleles in inherits from its parents. Some alleles are dominate, while others are recessive.
Types of Traits: Dominate vs. Recessive Dominate traits – a trait that always shows up when the dominate allele is present. Recessive traits – a trait that is present only when no dominate allele are present. Sometimes it is present but hidden.
How to represent dominate or recessive alleles. Dominate traits are capitalized. Ex. (Right handed = RH) Recessive traits are not capitalized. Ex. (Not right handed = rh)
Mendel – The Father of Genetics. Studied genetics by crossing pea plants. Found out traits are not a blend of their parents’ characteristics.
Different –otypes’ Phenotypes – organisms physical/visible traits. Genotypes – organisms genetic make up. Ex: Phenotypes could be – Brown eyes Genotype for that could be - BB
Types of Genotypes Homozygous – two identical alleles for a trait (Brown eyes – BB) Heterozygous – two different alleles for a trait (Brown eyes – Bb) Mendel called these hybrids
Codominance The alleles are neither recessive nor dominate, they both show up in an organisms offspring.
PUNNETT SQUARES Punnett square is a method for predicting the possible genotypes of offspring. Write the examples down that I do on the board.