chapter 3 notes - Chapter 3"Mendelian Genetics Inherited...

Info icon This preview shows pages 1–3. Sign up to view the full content.

Chapter 3 “Mendelian Genetics” Inherited characteristics are under the control of discrete particulate factors called genes that are transmitted from generation to generation on vehicles called chromosomes, according to rules first described by Gregor Johann Mendel. The outcomes of these rules are affected by chance deviation and can be evaluated using statistical analysis. Human traits are initially studied using the pedigree method. “Mendelian Genetics” 3.1 Gregor Johann Mendel 39 3.2 Monohybrid cross 39-43 3.3 Dihybrid cross 43-46 3.4 Trihybrid cross 46-47 3.5 Rediscovery of Mendel’s work 47-49 3.6 Independent assortment 49 3.7 Probability and genetic events 49-50 3.8 Evaluating genetic data-Chi square 50-52 P. 55 Tay-Sachs Disease 3.1 Gregor Johann Mendel Some highlights of Mendel’s life -He is considered the “Father of transmission genetics” -Born in 1822 to a peasant family in Heinzeldorf (Czech Republic). -Admitted to the Augustinian Monastery of St. Thomas in the Czech Republic -From 1851 to 1853 he studied physics and botany at the University of Vienna -He taught physics and natural sciences for the next 16 years -Began his hybridization of garden pea in 1856, -Terminated his experiments in 1868 when he was elected Abbot -First reported his results in 1865, but they went unnoticed until early in the 20 th Century -He died in 1884 of kidney failure. Why did Mendel succeed where others failed? 1. He chose the correct organism, the garden pea. Easy to grow and hybridize (large floral parts). Has a fairly short life cycle. Morphological traits are easily distinguished. See Figure 3-1 2. Chose traits that were controlled by single dominant genes. Flower color, seed texture, etc. He restricted his studies to these traits.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

3. Each trait was inherited independently. We will discuss this concept in Ch 7. See p. 157 4. He kept accurate and quantitative records. This allowed his hypotheses about ratios to be formulated. This was likely the most important reason that Mendel succeeded. Mendel in Modern Terms - Mendel did not coin the term “gene” - Mendel referred to “unit factors” for different forms of a gene (alleles) Gene = the unit of inheritance Allele= alternate forms of a gene 3.2 The Monohybrid Cross Monohybrid cross = Mono (one trait) hybrid (a cross between two dissimilar parents) Example Tall vs short pea plants controlled by a single gene Phenotypes: Tall vs Short This is Mendel’s First Postulate of Inheritance = Unit factors occur in pairs See Figure 3.2 Calculation of expected phenotypic frequencies based on frequency of gametes produced by parental genotypes Punnett Square An easy way to determine the expected phenotypic frequencies See Figure 3-3 Mendel’s First Three Postulates 1. Unit factors (alleles) occur in pairs
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.
  • Spring '08
  • BRICK
  • Genetics, Gregor Johann Mendel

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern