Slide 1 Inheritance & Human Genetic Patterns Chapter 12-13 Slide 2 Thomas Hunt Morgan EEarly 1900s UUsed fruit flies, Drosophila melanogaster to identify genetic patterns. OObserved that only male fruit flies had white eyes WHY?? Slide 3 Linkage groups A group of genes located on one chromosome. These genes are usually inherited together. Example: Fruit flies have 4 pairs of chromosomes & four linkage groups. How many linkage groups do humans have? Slide 4 Sex Determination Sex Chromosomes X & Y Located in 23 rd position (human) XX female XY - male Autosomes All other chromosomes Slide 5 Sex Linkage Traits that are linked to sex chromosomes. Slide 6 Gene Maps SShow the relative locations of each known gene on an organisms chromosome. Slide 7 Mutations CChange in DNA Germ cell mutation OOccurs in gametes DDo no affect the organism MMay be passed on offspring Somatic cell mutation OOccurs in body cells NNot passed to offspring LETHAL MUTATIONS: cause death usually before birth Slide 8 Gene mutations Involve a single nitrogen base or larger segment of DNA. Point Mutations Substitution, addition, or removal of a single nitrogen base Mutagen Environmental factor that damages DNA Ex. Carcinogens, tobacco, tars, UV radiation Slide 9 Chromosome Mutations Deletion Loss of a piece of chromosome Inversion Chromosome section breaks off & reattaches in reverse orientation. Slide 10 Chromosome Mutations cont Translocation Chromosome section breaks off & reattaches to another, non- homologous chromosome Nondisjunction Failure of a chromosome to separate during meiosis. Slide 11 Results of Nondisjunction Monosomy Zygote with 45 chromosomes Turners Syndrome (XO) Trisomy Zygote with 47 chromosomes Down Syndrome (Trisomy 21) Klinefelters Syndrome (XXY) Slide 12 Trisomy 21 Slide 13 Genetic Traits & Disorders Single Allele Traits (dominant) Huntingtons Disease, Achondroplasia (Dwarfism), Cataracts, Polydactyly Single Allele Traits (recessive) Albinism, PKU, Cystic Fibrosis, Hereditary deafness, Sickle cell anemia Slide 14 Genetic Traits continued X-linked Traits Colorblindness, hemophilia, muscular dystrophy, ichthyosis simplex Multiple Allele Traits Blood Types Polygenic Traits Skin, hair, & eye color; foot size, nose length, height Sex-influenced Traits Male pattern baldness Slide 15 Detecting Human Genetic Disorders Genetic Screening Examination of persons genetic makeup Genetic Counseling Amniocentesis Removal of amniotic fluid from mother Chorionic Villi Sampling Villi contain same genetic makeup of fetus Slide 16 Continued Karyotype Picture of an organisms chromosomes Ultrasound Bouncing sound waves off fetus to create an image Pedigree Family record that shows how traits are inherited over several generations Slide 17 Pedigree Slide 18 DNA Technology Genetic Engineering Used to identify genes for specific traits Transfer genes for a specific trait from one organism to another organism. Uses of DNA Technology Cure diseases Treat genetic disorders Improve good crops Slide 19 Transplanting Genes Isolate a gene (ex. Insulin) Produce recombinant DNA A combination of DNA from 2 or more sources. Clone DNA Allow bacteria time to reproduce Transgenic animal: A host organism receiving recombinant DNA Slide 20 The Human Genome Project Goals: To determine the nucleotide sequence of the entire human genome (approx. 3 billion nucleotide pairs or 100,000 genes) To map the location of every gene. Slide 21 Gene Therapy Treating a disorder by introducing a gene into a cell or by correcting a gene defect in a cells genome.