Chapter 6 Study Questions

  1. Distinguish amongst the following terms: (1) gene, (2) locus, (3) allele, (4) transcription unit.
  2. A flower geneticist crosses a red flowered diploid plant with a white flower diploid plant and all the progeny are red. Use two different forms of symbols to show this cross and its progeny. What if all the progeny were pink?
  3. If your blood type is B, what are the possible genotypes of your parents at the locus that controls the ABO blood types?
  4. In the table below, match the mouse hair colour phenotypes with the term from the list that best explains the observed phenotype, given the genotypes shown. In this case, the allele symbols do not imply anything about the dominance relationships between the alleles.
    List of terms: haplo-sufficiency, haplo-insufficiency, pleiotropy, incomplete dominance, co-dominance, incomplete penetrance, broad (variable) expressivity.

      A1A1 A1A2 A2A2
    1 all hairs black on the same individual:
    50% of hairs are all black and
    50% of hairs are all white
    all hairs white
    2 all hairs black all hairs are the same shade of grey all hairs white
    3 all hairs black all hairs black 50% of individuals have all white hairs and 50% of individuals have all black hairs
    4 all hairs black all hairs black mice have no hair
    5 all hairs black all hairs white all hairs white
    6 all hairs black all hairs black all hairs white
    7 all hairs black all hairs black hairs are a wide range of shades of grey

  5. In this hypothetical example of Drosophila bristle mutations, when various, true-breeding mutant strains (all at a single locus) are crossed to a wild type strain the following phenotypes are observed in the progeny:
    • Mutant#1 = bristles 20% shorter
    • Mutant#2 = bristles 30% longer
    • Mutant#3 = bristles 50% shorter
    • Mutant#4 = bristles kinked and misshapen
    • Mutant#5 = bristles are missing

    What is the best characterization, using Muller’s Morphs, for each?

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Open Genetics by Natasha Ramroop Singh, Thompson Rivers University is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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