Mendelian Inheritance Notes

• Genetics


  The study of heredity
• Gregor Mendel


  Father of Genetics
• Principle of Independent Assortment


  • Inheritance of one trait has no effect on the inheritance of another trait
• Rule of Unit Factors

  • There are factors that determine traits, we now know these as alleles
• Law of Segregation


  • Alleles separate (segregate) during gamete formation
• Genetics


  The study of how traits are passed from parent to offspring
• Traits


  Determined by the genes on the chromosome
• Chromosomes


  Come in homologous pairs, thus genes come in pairs
• Humans


  • Have 46 chromosomes or 23 pairs
• Homologous Chromosomes


  Matching genes - one from female parent and one from male parent
• Alleles


  Different genes for the same trait
• Dominant


  A gene that prevents the other gene from "showing"
• Recessive


  A gene that does not "show" even though it is present
• Straight thumb


  • Dominant to hitchhiker thumb
• Homozygous


  Both genes of a pair are the same
• Heterozygous


  One dominant and one recessive gene
• Genotype


  The actual gene makeup
• Phenotype


  The physical appearance resulting from genetic make-up
• True Breeding


  Organism has a pure genotype and will only produce offspring with the same trait
• Hybrid


  Organism produced by parents with two different traits, so trait could be seen in the offspring
• Punnett Squares


  Used to predict the possible gene makeup of offspring
• Marginal utility


  The additional utility (satisfaction) gained from the consumption of an additional product
• If you add up marginal utility for each unit you get total utility
• Incomplete Dominance


  When one allele is not completely dominant over another, they blend
• Codominance


  When both alleles are expressed
• Sex Determination


  22 pairs of homologous chromosomes determine body traits, 1 pair of sex chromosomes determines sex
• Sex-linked Traits


  Genes for these traits are located on the X chromosome, not the Y chromosome
• Multiple Alleles


  3 or more alleles of the same gene that code for a single trait
• Pedigrees


  Graphic representation of how a trait is passed from parents to offspring
• Polygenic Inheritance


  A trait that is controlled by 2 or more genes