MUTATION AND VARIATION

CUT OBJECTIVE 26!!! NON-MENDELIAN INHERITANCE - Mendelian = Complete Dominance - Only the dominant allele’s protein is produced - When a yellow and purple parent produce a purple offspring - Not all traits are simply determined by a single dominant and a single recessive allele. - Incomplete Dominance (see Diana’s picture) - A little of each allele’s protein is produced. - Codominance - A lot of each allele’s protein is produced. - Polygenic - Multiple genes determine the trait - Eye color - Bell Peppers - Colon Cancer - Human needs to have mutations in about 7 different genes. - Sex-Linked Traits - Gene for trait is on portion of “X” chromosomes not matched by “Y” COMPLEXITY - Variable Expression: All cells in an organism have the same genes, but only some are used. - Muscle Cell - Pancreatic Cell - Molecular “bookmarks” are put in each cell’s DNA to indicate which genes should be active. - Modifier Genes: Some genes can modify the effect of another gene. - Albino: Gene stops production of pigment proteins - Master Control Genes: Activate numerous genes to control complex tasks - Environmental Effects: A cell’s surroundings can impact how genes function - Diet and hormones - Which is a bigger influence: Genetics or Environment? (Nature vs Nurture) - Heterochromia: your eye has 2 distinct color MUTATIONS - Mutations produce new alleles (versions of genes) - Mutation: DNA is altered - “Big” Chromosomal Mutations - structured changes or irregular number (uncommon) - Base “Point” Mutation - common - Mutations in sperm and eggs can be passed on to future generations. - Causes of Mutations - Mistakes during DNA replication This study source was downloaded by from CourseH on :55:02 GMT -06:00 - Damage from external agents (mutagens) - Defenses Against Mutation - Mutation repair proteins - Effects of Mutations - Primary Impact: No change (in protein or cell function) - Less Frequent: Negative Impact - Rare: Positive Impact Day 6 1/24/2013 DEVELOPMENT EXAM ON MONDAY AT 7PM!!!! FRUIT FLIES - “Fruit Fly” Drosophila Melanogaster - Easy to care for - Short generation time (7+ days) - Large numbers of offspring - Identifiable mutations - Fruit fly mutations - Different eye color, eye shape, wings, color. larva, etc. - Thomas Hunt Morgan () - Demonstrated that genes are located on chromosomes. - Sex-linked traits - Crossing-over between chromosomes. - Famous for his paper where he talks about genetics and evolution. - Linked Mendel’s principles of inheritance and Darwin’s theory of natural selection as a means for transforming species. - Fruit Fly Genome - A genome is all of the hereditary information found in an organism. - # of Chromosomes: Fruit Flies 2N = 8, Humans 2N = 46 - # of Genes: Fruit Flies ~ 13,600, Humans ~ 23,000 - Fruit Fly Life Cycle - See Picture - Meiosis: only happens to produce sperm and eggs, just for sexual reproduction. - (2N - 1N) - Meiosis has an E and Sex has an E - Fertilization: (1N + 1N = 2N) - Mitosis: a cell make a genetic copy (2N - 2N) - Excessive Mitosis: Cancer GENES AND DEVELOPMENT - See Diana’s Pictures - Master Control Genes - HOX Genes: organize head, thorax, abdomen This study source was downloaded by from CourseH on :55:02 GM