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Multiple Cross Overs and Interference quiz #1 Flashcards

Multiple Cross Overs and Interference quiz #1
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  • Which of the following genetic phenomena is determined by multiple alleles?
    Traits such as ABO blood type in humans are determined by multiple alleles, where more than two alternative forms of a gene exist in the population.
  • The term 'multiple alleles' refers to the presence of how many alleles in the population?
    The term 'multiple alleles' refers to the presence of three or more alleles for a particular gene in the population.
  • What is a multiple crossover event in genetics?
    A multiple crossover event occurs when more than one crossover causes two or more changes in the gamete genotype, making detection more difficult and the events less frequent.
  • Why are double crossovers harder to detect than single crossovers?
    Double crossovers are harder to detect because they require knowledge of gene order and careful analysis, as they can mask the true recombination events between genes.
  • How do you calculate the expected frequency of double crossovers between two gene pairs?
    You multiply the individual crossover probabilities for each gene pair using the product law, then convert the result to a percentage.
  • What does the coefficient of coincidence (COC) measure in genetic mapping?
    The coefficient of coincidence measures the ratio of observed double recombinants to the expected number based on individual crossover probabilities.
  • How is genetic interference calculated using the coefficient of coincidence?
    Genetic interference is calculated as I = 1 - COC, where COC is the observed double crossovers divided by the expected double crossovers.
  • What does a positive interference value indicate about crossover events?
    A positive interference value indicates that fewer double crossovers occurred than expected, meaning a crossover in one region reduces the likelihood of another nearby.
  • Why is it important to double count double crossovers when calculating recombination frequency?
    Double counting double crossovers ensures accurate gene mapping by properly accounting for all recombination events between gene pairs.
  • What does it mean if the observed number of double crossovers is less than the expected number in an experiment?
    It means that interference has occurred, reducing the probability of double crossovers in adjacent gene regions compared to what was predicted.