Genetic Linkage in Drosophila Melanogaster
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Questions and Answers

What is the significance of a 50% recombination rate between two genes?

  • The genes are always unlinked and will never be inherited together.
  • The genes are located on the same chromosome but are very close together.
  • The genes are always linked and will never separate during crossing over.
  • The genes are on different chromosomes or are located far apart on the same chromosome. (correct)

    • What is the unit of measurement for recombination rates?

  • CentiMorgan (cM) (correct)
  • Morgan
  • Recombination fraction
  • Linkage frequency

    • What can be inferred about the relative positions of the eye colour, body colour, and wing size genes based on their recombination rates?

  • The genes are equally spaced from each other.
  • The eye colour and wing size genes are closest together.
  • The body colour and wing size genes are closest together.
  • The eye colour and body colour genes are closest together. (correct)

    • What is the relationship between recombination rate and physical distance between genes on a chromosome?

    <p>A lower recombination rate indicates genes are closer together.</p> Signup and view all the answers

    What is the purpose of generating a genetic linkage map?

    <p>To illustrate the relative positions of genes on a chromosome.</p> Signup and view all the answers

    What is the ratio of parental phenotypes expected in the offspring if linkage is complete?

    <p>1:1</p> Signup and view all the answers

    What is the primary reason for the absence of genetic consequences in chiasmata formation between sister chromatids in the same homologous chromosome?

    <p>They are identical</p> Signup and view all the answers

    What is the significance of the recombination rate of 17% in the Drosophila melanogaster cross?

    <p>It indicates that the genes are linked with a distance of 17 centiMorgan</p> Signup and view all the answers

    What is the process called when alleles from different genes come together in new combinations?

    <p>Genetic recombination</p> Signup and view all the answers

    What is the term for the visible crossing-over points between chromatids in a tetrad?

    <p>Chiasmata</p> Signup and view all the answers

    What is the purpose of creating a genetic map of genes on a chromosome?

    <p>To understand the inheritance patterns of traits</p> Signup and view all the answers

    Which of the following is a consequence of independent assortment of genes?

    <p>Genes are inherited independently</p> Signup and view all the answers

    What is the purpose of creating genetic linkage maps?

    <p>To locate genes on a chromosome and measure the distances between them</p> Signup and view all the answers

    What is the unit of measurement used to express the distance between genes on a chromosome?

    <p>Centimorgan</p> Signup and view all the answers

    What is the unit of measurement used to express the distance between genes on a genetic map?

    <p>CentiMorgan</p> Signup and view all the answers

    What is the chromosomal location of the genes OPN1MW and OPN1LW?

    <p>BTAX</p> Signup and view all the answers

    Which of the following is a characteristic of linked genes?

    <p>They are physically close to one another on the same chromosome</p> Signup and view all the answers

    What is the main reason why the wing size and body colour genes in Drosophila melanogaster are not sex-linked?

    <p>Because they are on the same autosomal chromosome</p> Signup and view all the answers

    What is the genotype of the wild type females used in the experiment by Thomas Hunt Morgan and his team?

    <p>b+ b+ vg+ vg+</p> Signup and view all the answers

    What is the phenomenon demonstrated by Thomas Hunt Morgan in Drosophila melanogaster?

    <p>Genetic Linkage</p> Signup and view all the answers

    What is the purpose of crossing wild type females with males that have both mutant phenotypes in the experiment?

    <p>To demonstrate genetic linkage between the two genes</p> Signup and view all the answers

    What is the significance of the superscript '+' symbol in Drosophila melanogaster gene notation?

    <p>It identifies the wild type allele for the eye color gene</p> Signup and view all the answers

    What is the unit of measurement for the distance between two genes on a genetic linkage map?

    <p>CentiMorgan units</p> Signup and view all the answers

    What is the relationship between the number of genes and the number of chromosomes?

    <p>The number of genes is much larger than the number of chromosomes</p> Signup and view all the answers

    What is the underlying principle of independent assortment, which is not observed in the case of genetic linkage?

    <p>Genes are distributed randomly during gamete formation</p> Signup and view all the answers

    What did Morgan's discovery of an eye color mutant lead to?

    <p>The first concrete demonstration that a gene is located on a specific chromosome</p> Signup and view all the answers

    What is the significance of the allele symbol 'w' in Drosophila melanogaster gene notation?

    <p>It represents the mutant allele for the eye color gene</p> Signup and view all the answers

    What is the relationship between the behavior of the sex chromosomes and the behavior of the two alleles of the eye color gene?

    <p>The behavior of the sex chromosomes can be correlated with the behavior of the two alleles of the eye color gene</p> Signup and view all the answers

    What is the purpose of correlating the behavior of the sex chromosomes with the behavior of the two alleles of the eye color gene?

    <p>To demonstrate the chromosome theory of inheritance</p> Signup and view all the answers

    What is the consequence of independent assortment of genes on a chromosome?

    <p>The recombination of alleles from different genes in new combinations</p> Signup and view all the answers

    What is the purpose of the Ishihara chart?

    <p>To diagnose sex-linked color blindness</p> Signup and view all the answers

    What is the result of Morgan's discovery of an eye color mutant in terms of genetic mapping?

    <p>The first concrete demonstration that a gene is located on a specific chromosome</p> Signup and view all the answers

    What is the relationship between the genetic distance between two genes and the recombination rate?

    <p>The genetic distance between two genes is inversely proportional to the recombination rate</p> Signup and view all the answers

    What is the significance of the centiMorgan unit in genetic mapping?

    <p>It is a measure of genetic distance between two genes</p> Signup and view all the answers

    What is the result of correlating the behavior of the sex chromosomes with the behavior of the two alleles of the eye color gene?

    <p>The support for the chromosome theory of inheritance</p> Signup and view all the answers

    What is the expected ratio of phenotypes if genes assort independently?

    <p>1:1:1:1</p> Signup and view all the answers

    What is the primary reason for the underrepresentation of recombinant phenotypes in Morgan's experiment?

    <p>Genes controlling body color and wing size are genetically linked</p> Signup and view all the answers

    What is the term used to describe the process of recombination between linked genes?

    <p>Crossing-over</p> Signup and view all the answers

    What is the unit of measurement used to express the distance between two genes on a chromosome?

    <p>CentiMorgan units</p> Signup and view all the answers

    What is the term used to describe the process of genes moving through meiosis as a unit without being separated by recombination?

    <p>Genetic linkage</p> Signup and view all the answers

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