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Questions and Answers
What is the most likely explanation for all the white-eyed flies in the F2 generation being male?
What is the most likely explanation for all the white-eyed flies in the F2 generation being male?
What does the chromosome theory of inheritance from the early 20th century state?
What does the chromosome theory of inheritance from the early 20th century state?
Why are males more often affected by sex-linked traits than females?
Why are males more often affected by sex-linked traits than females?
How is the SRY gene best described?
How is the SRY gene best described?
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What determines sex in birds?
What determines sex in birds?
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What causes black fur color in cats?
What causes black fur color in cats?
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What triggers male development in fruit flies?
What triggers male development in fruit flies?
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What causes red-green color blindness in humans?
What causes red-green color blindness in humans?
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What leads to tortoiseshell fur color in cats?
What leads to tortoiseshell fur color in cats?
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What determines gender differentiation in mammals?
What determines gender differentiation in mammals?
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When does clear gender differentiation in humans occur?
When does clear gender differentiation in humans occur?
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What causes Duchenne muscular dystrophy in humans?
What causes Duchenne muscular dystrophy in humans?
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What leads to cinnabar eye color in fruit flies?
What leads to cinnabar eye color in fruit flies?
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What causes the requirement for expression of genes on the Y chromosome in humans?
What causes the requirement for expression of genes on the Y chromosome in humans?
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How many active X chromosomes do female mammals have per cell?
How many active X chromosomes do female mammals have per cell?
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What determines sex in humans?
What determines sex in humans?
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What is the inheritance pattern of Glucose-6-phosphate dehydrogenase deficiency (G6PD) in humans?
What is the inheritance pattern of Glucose-6-phosphate dehydrogenase deficiency (G6PD) in humans?
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In a Drosophila experiment, how is the mutant allele for yellow body inherited?
In a Drosophila experiment, how is the mutant allele for yellow body inherited?
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What does a recombination frequency of 50% indicate about the location of two genes?
What does a recombination frequency of 50% indicate about the location of two genes?
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What is the relationship between gene linkage and probability of crossover?
What is the relationship between gene linkage and probability of crossover?
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What is the proportion of sons expected to have G6PD if a woman with an affected father marries a man with the disease?
What is the proportion of sons expected to have G6PD if a woman with an affected father marries a man with the disease?
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What does a testcross involving F1 dihybrid flies producing more parental-type offspring than recombinant-type offspring indicate?
What does a testcross involving F1 dihybrid flies producing more parental-type offspring than recombinant-type offspring indicate?
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What is the adaptive advantage of recombination between linked genes?
What is the adaptive advantage of recombination between linked genes?
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What is the significance of one map unit in linkage mapping?
What is the significance of one map unit in linkage mapping?
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Why can map units on a linkage map not be relied upon to calculate physical distances on a chromosome?
Why can map units on a linkage map not be relied upon to calculate physical distances on a chromosome?
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What is the order of the genes on a chromosome map in a series of mapping experiments for Drosophila?
What is the order of the genes on a chromosome map in a series of mapping experiments for Drosophila?
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What is the expected phenotype of a woman with 47 chromosomes, including three X chromosomes?
What is the expected phenotype of a woman with 47 chromosomes, including three X chromosomes?
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What process is primarily affected by mutations in mitochondrial genes?
What process is primarily affected by mutations in mitochondrial genes?
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What phenomenon explains the pattern of inheritance where the inheritance of variegated color on the leaves of certain plants is determined only by the maternal parent?
What phenomenon explains the pattern of inheritance where the inheritance of variegated color on the leaves of certain plants is determined only by the maternal parent?
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What is the most likely result of a defect in meiosis that results in the failure of spindle microtubules binding at the kinetochores?
What is the most likely result of a defect in meiosis that results in the failure of spindle microtubules binding at the kinetochores?
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If a pair of homologous chromosomes fails to separate during meiosis I, what is the chromosome number of the four resulting gametes with respect to the normal haploid number (n)?
If a pair of homologous chromosomes fails to separate during meiosis I, what is the chromosome number of the four resulting gametes with respect to the normal haploid number (n)?
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What is the most likely mode of inheritance in the transmission of a trait in a particular family shown in the pedigree?
What is the most likely mode of inheritance in the transmission of a trait in a particular family shown in the pedigree?
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What genotype(s) and phenotype(s) will offspring have if a Dd egg-producing snail and a dd sperm-producing snail reproduce?
What genotype(s) and phenotype(s) will offspring have if a Dd egg-producing snail and a dd sperm-producing snail reproduce?
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What is the approximate distance between genes A and B based on the recombination frequency?
What is the approximate distance between genes A and B based on the recombination frequency?
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What is the term for a fragment joining a nonhomologous chromosome, which can lead to expression of inappropriate gene products in cancer cells?
What is the term for a fragment joining a nonhomologous chromosome, which can lead to expression of inappropriate gene products in cancer cells?
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What is the most probable cause of a child with Down syndrome, born to a 39-year-old mother?
What is the most probable cause of a child with Down syndrome, born to a 39-year-old mother?
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What is the impact of trisomy 21 (47, trisomy 21) among the given aneuploidies?
What is the impact of trisomy 21 (47, trisomy 21) among the given aneuploidies?
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What is the inheritance pattern of Glucose-6-phosphate dehydrogenase deficiency (G6PD) in humans?
What is the inheritance pattern of Glucose-6-phosphate dehydrogenase deficiency (G6PD) in humans?
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What would result from a balanced translocation in the father's chromosome 4 and 12?
What would result from a balanced translocation in the father's chromosome 4 and 12?
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What would result from nondisjunction of one chromosome during meiosis II in cell X?
What would result from nondisjunction of one chromosome during meiosis II in cell X?
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What does a testcross involving F1 dihybrid flies producing more parental-type offspring than recombinant-type offspring indicate?
What does a testcross involving F1 dihybrid flies producing more parental-type offspring than recombinant-type offspring indicate?
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What is the term for the expression of inappropriate gene products in malignant tumors, such as translocations?
What is the term for the expression of inappropriate gene products in malignant tumors, such as translocations?
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What would be the result of a recombination frequency of 50% between two genes?
What would be the result of a recombination frequency of 50% between two genes?
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What would a testcross progeny of gray-bodied, normal-winged flies plus black-bodied, vestigial-winged flies equalling 17% of the total indicate?
What would a testcross progeny of gray-bodied, normal-winged flies plus black-bodied, vestigial-winged flies equalling 17% of the total indicate?
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Study Notes
Genetics and Inheritance Summary
- Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as an X-linked recessive allele in humans.
- A woman with a G6PD affected father marries a man with the disease; proportion of their sons expected to have the disease is 1/2.
- In a Drosophila experiment, a mutant allele for yellow body is inherited as recessive.
- Mutant allele for yellow body in Drosophila is X-linked.
- Gene linkage: closer genes on a chromosome have lower probability of crossover.
- In a testcross involving F1 dihybrid flies, more parental-type offspring than recombinant-type offspring are produced; the two genes are closely linked on the same chromosome.
- Recombination frequency of 50% indicates that the two genes are likely located on different chromosomes.
- One map unit is a 1% frequency of recombination between two genes.
- Recombination between linked genes comes about through crossovers resulting in chromosomal exchange.
- Adaptive advantage of recombination between linked genes: new allele combinations are acted upon by natural selection.
- Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome due to the varying frequency of crossing over along the chromosome.
- In a series of mapping experiments for Drosophila, the order of the genes on a chromosome map is b-rb-cn-vg.
Genetic Cross and Linkage Summary
- A geneticist performed a testcross with an organism heterozygous for three recessive traits and identified progeny with specific phenotypic distributions.
- Recombination between genes A and B was required for progeny phenotypes 1, 2, 5, and 6.
- The approximate distance between genes A and B was 3 map units based on recombination frequency.
- Closely linked genes are typically inherited together because they are located close together on the same chromosome.
- In a testcross, the distance between genes was found to be 15 map units.
- In Drosophila melanogaster, testcross progeny showed that gray-bodied, normal-winged flies plus black-bodied, vestigial-winged flies equaled 17% of the total.
- Nondisjunction of one chromosome during meiosis II in cell X would result in one-quarter of the gametes being n + 1, one-quarter being n - 1, and half being n.
- A fragment joining a nonhomologous chromosome is called translocation, which can lead to expression of inappropriate gene products in cancer cells.
- Trisomy 21 (47, trisomy 21) generally has the most severe impact on the health of an individual among the given aneuploidies.
- A balanced translocation in the father's chromosome 4 and 12 will result in one-quarter of sperm carrying the normal chromosomes, one-quarter carrying only the translocation chromosomes, and half carrying one normal and one translocated chromosome.
- Abnormal chromosomes in malignant tumors, such as translocations, may lead to the expression of inappropriate gene products, making the cancer worse.
- The most probable cause of a child with Down syndrome, born to a 39-year-old mother, is one member of the couple undergoing nondisjunction in somatic cell production.
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Description
Test your knowledge of genetics and inheritance with this quiz. Explore concepts such as X-linked inheritance, gene linkage, recombination, genetic crosses, aneuploidies, and chromosomal aberrations. Sharpen your understanding of genetic principles and their applications through a series of challenging questions.