Chapter 14: Mendel and the Gene Idea

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

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 – M,N,MN blood groups Multiple alleles – ABO blood groups Surface carbohydrate Alleles

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 – Cystic Fibrosis – Sickle Cell Anemia – Phenylketonuria (PKU) Dominant – Achondroplasia – Huntington’s Multifactorial – Heart disease, diabetes, cancer, alcoholism, schizophrenia, manic-depressive disorder

Chapter 15: The Chromosomal Basis of Inheritance

Thomas Morgan’s Experiment White type restricted to males – Sex-linked Recessive- – Father to son – Linked genes Passed as unit Same chromosome

Sex-Linked Disorders Duchenne’s – Loss of muscle strength and coordination Hemophilia – Failure of blood to clot Red-green colorblindness – Primarily males

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

Chromosomal Complications Deletion – Cri-du-chat Translocation – Chronic myelogenous leukemia Inversions Duplications

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 = ∑ (o – e) 2 e

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