Genetic Terminology Character – Trait True-breeding Hybridization – P generation – F 1 generation – F 2 generation

Mendel’s Ideas For each trait an organism inherits two alleles If the alleles are different… – Dominant – Recessive Test Cross

Mendel’s Laws Law of Segregation – Alleles for each character separate during gamete formation

Mendel’s Laws Law of independent assortment – Pairs of alleles separate individually

Rules of Probability Rule of multiplication – Examples 2 coins land heads up Parent is YyRr, gamete will carry Y, R Parents are YyRr, offspring will be YYRR Rule of Addition – Event can occur two or more ways – Example Two ways to produce heterozygote if parents are Pp

Rules of Probability PpYyRr x Ppyyrr What is the probability of offspring having recessive phenotype for at least two of the three traits – ppyyRr – ppYyrr – Ppyyrr – PPyyrr – ppyyrr

Types of Inhertiance Incomplete dominance – Snapdragons Co-dominance – ABO blood groups

Types of Inheritance Pleiotropy – Sickle Cell Anemia Epistasis – Coat color in mice Polygenic traits – Eye color – Skin color

Pedigrees

Genetic Disorders Recessive – Tay Sachs Dominant – Huntington’s Multifactorial – Heart disease, diabetes, cancer, alcoholism, schizophrenia, manic-depressive disorder

Chromosomal Complications Non-disjunction – Aneuploidy Trisomy – Down’s Syndrome – Klinefelter’s Syndrome

Sex-Linked Disorders Hemophilia – Failure of blood to clot Red-green colorblindness – Primarily males

Chi Square Analysis Used to determine if there are deviations for the phenotypic ratio of the F 2 generation within the limits expected by chance – Null hypothesis – Formula X 2 = S (o – e) 2 e

Chi Square Analysis Degrees of freedom Chi square – Critical value Reject hypothesis Probability

Add Linked genes Screening