Genetics, Ch.7

24 July 2022
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The recombinant gremlins of the F2 generation were produced by crossing over that occurred:
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during spermatogenesis in the F1 males.
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A crossover in meiosis is an exchange of genetic material between _____. sister chromatids of nonhomologous chromosomes sister chromatids of homologous chromosomes non-sister chromatids of nonhomologous chromosomes sister chromatids of the same chromosome non-sister chromatids of homologous chromosomes
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non-sister chromatids of homologous chromosomes Homologous chromosomes can exchange pieces with each other during a phenomenon called crossing over.
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A tetrad is made up of _____. two homologous chromosomes, each consisting of two chromatids four nonhomologous chromosomes four homologous pairs of chromosomes four nonhomologous chromatids
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two homologous chromosomes, each consisting of two chromatids
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Which of the following statements about crossing over is TRUE? It occurs only in some chromosomes. It occurs only between genes that are heterozygous. It occurs only in males. None of these choices are correct. It results in reduced genetic variation among gametes.
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None of these choices are correct.
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Crossing over occurs during prophase I of meiosis. True False
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true
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Refer to the cross done in the interactive exercise on linkage to answer this question. If, when counting the F1 progeny, you did not separate the two nonrecombinant (parental) progeny classes by gender, hypothetically, how many of each nonrecombinant class would then be present in those two groups? There would be the same number in each nonrecombinant class grouping. There would be twice as many in each nonrecombinant class grouping. There would be half as many in each nonrecombinant class grouping. There would no longer be any nonrecombinant flies to count.
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There would be twice as many in each nonrecombinant class grouping.
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If a gray-bodied, red-eyed female with genotype Xy+w+Xyw were mated to a gray-bodied, red-eyed male with genotype Xy+w+Y, which phenotypic class would be counted as a recombinant in the F1 progeny? yellow-bodied, white-eyed males yellow-bodied, red-eyed males yellow-bodied, white-eyed females red-bodied, white-eyed females
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yellow-bodied, red-eyed males
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A diagram that depicts the sequence of genes along a chromosome is called a ________________ ________
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genetic map
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Two or more genes that are located on the same chromosome are _______________
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syntenic
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When genes that are close together on the same chromosome are transmitted as a unit it is called _________________ ________________
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genetic linkage
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An entire chromosome is considered a _______________ ____________, as it contains a group of genes that are physically linked together.
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linkage group
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In each species, the number of linkage groups equals the _________________ number of chromosome types.
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haploid
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true or false A genetic map allows geneticists to understand the overall complexity and genetic organization of a particular species.
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true
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true or false Knowing the locus of a gene within a genetic map can help molecular geneticists clone the gene
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true
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true or false Genetic maps can be used to improve our understanding of the evolutionary relationships among species.
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true
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true or false Genetic maps can be used to diagnose and perhaps someday treat inherited human diseases.
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true
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true or false Genetic counselors can use genetic maps to determine if an individual will express a particular gene.
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false
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true or false Genetic maps provide plant and animal breeders with helpful information for improving agriculturally important strains through selective breeding programs.
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true
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Which of the following hypotheses is best to determine if the genes that Morgan studied for eye color and body color are linked or if they assort independently?
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The two genes for eye color and body color obey Mendel's law of independent assortment.
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Based on the hypothesis that the two genes for eye color and body color obey Mendel's law of independent assortment, calculate the expected values of each of the four phenotypes. (Use the actual and expected data shown to the left) total is 2,205 of F2 generation. expected Mendelian ratios= 1:1:1:1
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The expected number of offspring with each phenotype is 551.
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Determine the Chi square value for the data using the equation provided in the text. 1,159 17 12 1,017
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X2 = 2110
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. Based on a X2 value of 2110, the hypothesis that the two genes for eye color and body color obey Mendel's law of independent assortment, should be:
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rejected
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-diagram that describes the order of genes along a chromosome
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genetic map
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-two or more genes are located on the same chromosome -physically linked to each other, because each eukaryotic chromosome contains a single, continuous, linear molecule of DNA
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synteny
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-genes that are close together on the same chromosome tend to be transmitted as a unit
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genetic linkage or simply linkage
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-chromosome contains a group of genes that are physically linked together
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linkage groups
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-two pairs of sister chromatids
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bivalent
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-two haploid cells that carry the dominant A and B alleles and the other two carry the recessive a and b alleles
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nonrecombinant cells
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-two of the haploid cells contain combinations of alleles, namely A and b or a and B, which differ from those in the original chromosomes -leads to a new combination of alleles because the grouping of linked alleles has changed
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genetic recombination
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-assumes there is no real difference between the observed and expected values
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null hypothesis
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-site where the gene is found within a particular chromosome
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locus
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-frequency of recombinant offspring due to crossing over provides a way to deduce the linear order of genes along a chromosome
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genetic linkage map
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-between an individual that is heterozygous for two or more genes and an individual that is recessive and homozygous for the same genes -determine if recombination has occurred during meiosis in the heterozygous parent
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testcross
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-defined as the number of recombinant offspring divided by the total number of offspring, multiplied by 100
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map distance
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-describe the quantitative relationship between recombination frequencies and physical distances along chromosomes
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mapping functions
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-mitotic crossing over may produce a pair of recombinant chromosomes that have a new combination of alleles
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mitotic recombination