ZOL 141 1st Edition Lecture 11Outline of Last Lecture I. Experimental SetupII. Experiments and ResultsIII. Branch Diagrama. Probability RulesIV. ProbabilityOutline of Current Lecture II. Genes and ChromosomesIII. Mendelian inheritance in humansA. PedigreesB. Albinisma. Symptomsb. causesC. Hereditary Deafnessa. Symptomsb. causesIV. Principles of Independent AssortmentV. Branch DiagramsCurrent LectureMendel’s Laws and Meiosis:Genes are on chromosomesChromosome theory of inheritance- 1903- Sutton and Boveri independently proposed genes must be located on chromosomes- Genes vs. chromosomes -Independent assortment occurs in metaphase 1After meiosis 1: cells are haploid. N=2Mendelian inheritance in humans- Pedigree- Albinismo Symptoms: Reduction in amount of melanin pigment formed in the skin, hair, and/or eyes All forms are associated with vision problems Occur in all racial and ethnic groups 1/18000 people in USo Causes: Oculocutaneous albinism (OCA1) Mutation in TYR gene that encodes enzyme tyrosinase Tyrosinase converts tyrosine into melanino Autosomal recessive: Have one wild type (normal) allele can make enough pigment for normal coloring Homozygotes for mutant allele have albino phenotype Unaffected individuals can have affected child- Principle of segregationo Heterozygous=carriero Gamete formation: equal chance either allele by parentso Gamete combinations represent random fertilizationo Same as peas!- Hereditary deafnesso Symptoms: Hearing loss inherited by children from their parents Syndromic: associated with other symptoms Non-syndromic: not associated with other symptoms 1/1000 children in US, 50% genetico Causes: Mutations in many genes can cause hereditary deaness GJB2 gene encodes gap junction beta 2 (connexin 26) Important function in cochlea Cochlea converts physical vibrations Autosomal recessive- Principle of independent assortmento Parents heterozygous for albinism (A,a)o Heterozygous for deafness (D, wild type (dominant) and d, mutant (recessive))o 9/16 pigmented and hearingo 3/16 pigmented and deafo 3/16 albino and hearingo 1/16 albino and deaf- Branch diagram (same as