Genetics The study of heredity polydactyly

Heredity The passing on of traits (characteristics) from parents to offspring China McClain & sisters (Ant Farm)

Examples of Traits Hair color Eye color Height Intelligence Ability to roll your tongue Mid-digital hair Attachment of ear lobe Ability to taste bitter

Traits are controlled by genes …. so then what are genes? Gene Controls how an organism develops It is a specific segment of DNA located on a chromosome Each trait has two alleles …. so then what are alleles? Allele Different forms of the same gene How are genes passed on? By your parents in reprododo

Alleles Dominant allele Recessive allele Produces a trait that is observed in the offspring whenever present Represented with an uppercase letter Recessive allele produces a trait that is observed in the offspring only if both alleles are recessive. Otherwise, the trait disappears Represented with a lowercase letter

--The separation of alleles during meiosis to form gametes --The separation of alleles during meiosis to form gametes. ( Sex cells: egg/sperm) The law of independent assortment states that genes for different traits can segregate or switch independently during the formation of gamates.

For example: Eye Color Dominant Color: Brown = B Recessive Color : Blue = b One allele from each parent because two alleles form a trait, therefore… B B b b B b Brown Blue Brown

Phenotype BB bb Bb The way an organism looks (physical) For example: BB bb Bb Phenotype: Brown Blue Brown

Genotype Homozygous (same) Heterozygous (one of each) BB bb Bb The gene combination of an organism (genes) Homozygous (same) If the two alleles of a trait are the same (BB or bb) Heterozygous (one of each) If the two alleles for a trait are different (Bb) For example: BB bb Bb Genotype: Homozygous Dominant Homozygous recessive Heterozygous

How did we figure this stuff out?! Gregor Mendel was a monk from Austria born in 1822 He made observations of his father’s orchard and decided he could predict the kinds of flowers a plant could produce…if he knew something about the parent plants. After 8 years of carefully carrying out the scientific method, Mendel wrote a paper about inheritance in pea plants.

Traits of Pea Plants

Punnett Square Diagram used to predict genetic crosses.

b b b Individuals with identical alleles are called homozygous. Individuals with different alleles are called heterozygous. Phenotype-physical characteristics Genotype-genetic makeup How to use a Punnett Square -choose a letter to represent the alleles in the cross -write the genotypes of the parents -determine the possible gametes (reproductive cells)that the parents can Produce. -enter the possible gametes at the top and side of the Punnett Square b b b