2 Some definitions to know Gregor Mendel - the Father of GeneticsTrait - a characteristic that can be passed to offspringGenotype – the pair of genes that make up a trait (one from mom, one from dad)Aa, AA, aaPhenotype – What the trait looks likeBlack or brown fur color
3 Independent assortment means that genes are separated during meiosis, and each egg and sperm is unique.
4 Punnett squares are used to predict the genotype and phenotype of the offspring
6 A test cross is used to determine the genotype of an unknown parent
7 Types of Dominance Complete One allele is dominant and one is recessiveB allele for black furb allele for brown furIf the genotype is Bb, the fur would be black, because black is dominant
8 Practice crosses Flower Red is dominant White is recessive Cross a homozygous dominant red flower with a heterozygous red flower.What are the genotypic and phenotypic ratios?SeedsGreen is dominantYellow is recessiveCross a homozygous recessive yellow seed with a homozygous dominant green seed.What are the genotypic and phenotypic ratios?
9 Types of Dominance Incomplete When neither allele is dominant and the phenotype is intermediate or a blend of the two alleles.R is the allele for red flowersR’ is the allele for white flowersThe genotype RR’ would produce pink flowers
10 Incomplete Dominance Long water melon (LL) * Round watermelon (L’L’) Do the crossWhat is the genotypic ratio?What is the phenotypic ratio?Remember – The phenotype in this case has 3 possibilities, LL long : L’L’ round: LL’ oval
11 Types of Dominance Codominance When both alleles are dominant and each allele is expressed in the traitType AB blood has both A and B antigens on it
13 Multiple alleles vs. polygenic inheritance more than 2 forms of a geneBloodtype allelesIAIBiPolygenic inheritanceWhen two or more genes work together to give you one traitEx. Hair and eye color
14 Sex linked genes are on the sex chromosomes (colorblindness and hemophilia) XX = normal femaleXhX = carrrier femaleXhXh = hemophiliac femaleA female who is a carrier does not have that trait! She is not sick at all. She won’t even know that she carries that gene.XY = normal maleXhY = hemophiliac maleMales only have I X chromosome.They cannot be carriers.This is why sex linked disorders are more common in men
15 Pedigrees show the inheritance of traits through families