Chapter 10 - Observable Patterns of Inheritance

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  1. Textbook website:
    1. outline, quiz, and flash cards: select from resources for chapter 10.
  2. STARR and TAGGART 9th edition website:
    1. outline, quiz, and flash cards: select from resources for chapter 11.
  3. STARR AN TAGGART 10th edition website:
    1. outline, quiz, and flash cards: select from resources for chapter 11.
  4. Mendelian Genetics many excellent links from Ken House's BioWeb
  5.  On-Line Biology Book by M. J. Farabee 
    1. Introduction to Genetics 
    2. Gene Interactions
  6. Kimball's Biology Pages
    1. Mendel's Monohybrid Cross from Kimball's Biology Pages
    2. Genetic Linkage and Genetic Maps from Kimball's Biology Pages
    3. Gene Mapping with a Three Point Cross from Kimball's Biology Pages
    4. Blood groups
  7. The Biology Project  an interactive online resource for learning biology, developed at The University of Arizona
    1. Mendelian Genetics
    2. Monohybrid Cross
    3. Dihybrid Cross
    4. Blood Types
  8. MIT Biology Hypertext 
    1. Introduction to Mendelian Genetics
    2. Analyzing Crosses
  9. North Harris College Genetics Tutorials
    1. Monohybrid Cross
    2. Dihybrid Cross
    3. Test Cross
  10. Kansas State
  11. Mendel Web
  12. The Blood and Immunity from Clarenville High's best Biology 2201 class.

Chapter Outline

MENDELIAN PATTERNS OF INHERITANCE Chapter 11

  1. Smorgasbord of Ears and Other Traits 1. Attached earlobes (Figure 11.1) are a recessive trait
11.1 MENDEL'S INSIGHT INTO PATTERNS OF INHERITENCE 
  1. Before Mendel
    1. blending inheritance
      1. Posed problems for Darwin's natural selection
  2.  Gregor Mendel's [fig. 11.1] Experimental Approach 
    1. particulate inheritance 
    2. Pisium sativum: the garden pea [fig. 11.2] 
      1. Controlled pollination
      2. Self fertilization > true-breeding
      3. Cross fertilization experiments
  3.  Modern Terminology [fig. 11.3] 
    1. Genes
    2. gene locus
    3. alleles
      1. dominant 
      2. recessive 
      3. homozygous
      4. heterozygous
    4.  genotype
    5. phenotype
    6. P = parental generation; F1 = first-generation offspring; F2 = second-generation offspring.

11.2 MENDEL'S THEORY OF SEGREGATION 

  1. Monohybrid Crosses
    1. P: two homozygous individuals differing in a single character:  reciprocal crosses >
    2. F1 (first filial) generation: heterozygous offspring 
    3. F2 generation: self pollination of F1 [11.5]
  2.  Punnet Square (fig 11.6; 11.7) 
    1. 3:1  ratio of phenotypes
    2. 1:2:1 ratio of genotypes
  3. The Monohybrid Testcross
    1. determine if a dominant phenotype is heterozygous or homozygous by crossing it with a recessive phenotype 
  4. Mendel's Law's (as rediscovered by Correns, de Vries, Tschermak) 
    1. Heredity transmitted by paired unit factors (genes) 
    2. Law of Segregation: each gamete receives only one gene from each pair. When fertilization occurs the zygote will have two factors, one from each parent. 
    3. Law of Dominance: when two alternatives are present, only one is usually expressed

11.3 INDEPENDENT ASSORTMENT

  1. Dihybrid Inheritence
    1. different alleles at two independent loci 
    2. Law of Independent Assortment [fig 11.8]
  2.  Dihybrid Cross [fig 11.9] 
    1. CCEE X ccee CcEe (P) --> CcEe (F1)
    2. CcEe X CcEe 
      1. 4 kinds of gametes: CE, Ce, cE, & ce
      2. 4 phenotypes: 9 (CE) : 3(Ce) : 3(cE) ; 1 (ce) 
      3. 16 possible genotypes (fig 11.9) 
  3. Dihybrid Testcross 
    1. L_G_ X llgg
    2. LlGg X llgg 1:1:1:1 phenotypes

11.4 DOMINANCE RELATIONS 

  1. incomplete dominance 
    1. intermediate phenotype in F1; characters reappear in F2 (fig 11.10) 
      1. F1 pink flowers from red and white parents 
        • F2 = .25R + .50P + .25W 
      2. roan horses and cattle: red incompletely dominant to white 
  2. ABO Blood Types: Codominance
    1. A and B genes fully expressed; e.g. AB blood group 
    2. Multiple alleles: more than two alternative forms.
      1.  ABO blood groups [Fig. 11.11] 
      2. IA and IB codominant, i recessive [Type O = ii]

11.5 MULTIPLE EFFECTS OF SINGLE GENES 

  1. Pleiotropy: a single gene locus affects many traits
    1. sickle cell anemia [fig 11.12] 

11.6 INTERACTION BETWEEN GENE PAIRS (Two Nonallelic Genes) 

  1. Epistasis - one gene affects the phenotypic expression of the other gene 
    1. Hair Color in Mammals [fig 11.13] 
      1. Gene B (black) greater effect in melanin production than b (brown)
      2. Gene E determines whether melanin will be deposited in hair 
      3. B_E_ (black labrador);  bbE_ (chocolate lab);  __ee (yellow lab) 
      4. albinism (fig 11.14)
        • Gene C codes for tyrosinase; recessive gene prevents formation of melanin
    2. Comb Shape in Poultry [fig 11.15] 
      1. R_P_ walnut comb; b. R_pp rose comb;  rrP_ pea comb;  rrpp single comb 

11.7 LESS PREDICTABLE VARIATION 

  1. Incomplete penetrance: dominant only expressed under certain conditions
    1. camptodactyly 
  2. Continuous Variation
    1.  Polygenic Inheritance (fig 11.16; 11.17) 
      1. Polygeny: a single trait (e.g. eye or skin color; height) is affected by several genes
      2. each allele adds quantitatively continuous distribution
      3. confused pattern of inheritence for eye color, height, weight, blood pressure, susceptibility to certain physical and mental diseases, intelligence. 

11.8 ENVIRONMENTAL EFFECTS ON PHENOTYPE 

  1. Siamese cats and Himalayan rabbits [fig 11.18] - temperature sensitive enzymes 
  2. Flower color in Hydrangia depends on soil pH [Fig. 11.19]

KEY TERMS FOR CHAPTER 11

Genetics Problems that have been asked on previous exams

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