Inheritance & Human Genetic Patterns Chapter 12-13
Thomas Hunt Morgan EEarly 1900s UUsed fruit flies, Drosophila melanogaster to identify genetic patterns. OObserved that only male fruit flies had white eyes WHY??
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?
Sex Determination Sex Chromosomes X & Y Located in 23 rd position (human) XX female XY - male Autosomes All other chromosomes
Sex Linkage Traits that are linked to sex chromosomes.
Gene Maps SShow the relative locations of each known gene on an organisms chromosome.
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
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
Chromosome Mutations Deletion Loss of a piece of chromosome Inversion Chromosome section breaks off & reattaches in reverse orientation.
Chromosome Mutations cont Translocation Chromosome section breaks off & reattaches to another, non- homologous chromosome Nondisjunction Failure of a chromosome to separate during meiosis.
Results of Nondisjunction Monosomy Zygote with 45 chromosomes Turners Syndrome (XO) Trisomy Zygote with 47 chromosomes Down Syndrome (Trisomy 21) Klinefelters Syndrome (XXY)
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
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
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
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
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.
Gene Therapy Treating a disorder by introducing a gene into a cell or by correcting a gene defect in a cells genome.