Mendelian Genetics

The Father of Genetics Gregor Mendel A monk that worked with pea genetics. –Purple vs. White - Flowers –Yellow vs. Green- Pea Color –Round vs. Wrinkled- Pea Shape –Tall vs. Short- Plant Size Genetics is the study of how traits are passed to offspring.

The Father of Genetics 1.Gregor Mendel discovered that different versions (alleles) of traits exist. 2.For each trait an organism inherits one version (allele) from each parent. 3.If the two versions (alleles) are different then one dominates over the other. 4.The two versions (alleles) separate during gamete production.

Genes and Traits GenesproteintraitGenes code for protein that makes a trait. There can be different versions of a trait. traitEX: eye color is a trait. Blue Green Brown allelesThese are different versions of the trait eye color. Different versions are called alleles.

Chromosomes and Genes Homologous chromosomes – one from mom and one from dad. Both have the same genes but each can have different alleles (different versions of the same gene).

Chromosomes and Genes PhenotypePhenotype = trait = nose size GenotypeGenotype = gene letters = GG Maternal chromosome can have G or g (big or small) Fraternal chromosome can have G or g (big or small) G G g g g G Gg

Chromosomes and Genes dominantG is dominant over g GG or Gg = a big nose recessiveg is recessive under G gg = a small nose heterozygousGg = heterozygous (different)(hybrid) homozygousGG or gg = homozygous (same)(pure breed) G G g g g G Gg

What kind of gametes can we get? Gametes are made by what process? Meiosis!

Punnet Squares Take the genotype of both parents. EX: father = Gg x mother = gg During meiosis and gamete production the two alleles are separated. (independent assortment) Gg gg GG will produce these gametes. gg will produce these gametes. Which two gametes will form a zygote?

Dominant: ( ) ______________________ Recessive: ( ) ______________________ Parents: GG X gg Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Punnet Squares

Dominant: ( ) ______________________ Recessive: ( ) ______________________ Parents: Gg X Gg Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Punnet Squares

P  F 1  F 2 P = parents (GG gg) F1 = 100% Gg & big nose F 2 = 3:1 phenotype F 2 = 1:2:1 genotype Gg g g GG Mom’s gametes Dad’s gametes GgGG G ggGg g gG Mom’s gametes Dad’s gametes

PROBABILITY If I flip a coin. What can I get? Heads or Tails If I flip a coin 10 times what should I get? 5 Heads & 5 Tails? How many times can I get a heads? Can I get 10 heads?

Boy or Girl? 50/50 Each time a couple mates there is a 50/50 chance of getting a boy or a girl. If the same couple has 10 kids what are they most likely to have? 5 boys and 5 girls Is it possible to have 10 boys? Yes Is it likely? No