6. Chromosomal Variation
Chromosomal Mutations: Aneuploidy
- Open QuestionWhat evidence indicates that humans with aneuploid karyotypes occur at conception but are usually inviable?
- Open Question
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
monosomy - Open Question
If the haploid number for a plant species is 4, how many chromosomes are found in a member of the species that has one of the following characteristics? Explain your reasoning in each case.
monosomy - Open Question
If the haploid number for a plant species is 4, how many chromosomes are found in a member of the species that has one of the following characteristics? Explain your reasoning in each case.
trisomy - Open QuestionDescribe how nondisjunction in human female gametes can give rise to Klinefelter and Turner syndrome offspring following fertilization by a normal male gamete.
- Open Question
The most common reason a physician might recommend that a woman have maternal serum screening and a karyotype analysis is concern that her fetus may have Down syndrome. Go to the OMIM website at www.ncbi.nlm.nih.gov/omim and look up Down syndrome (OMIM 190685).
List the main symptoms of Down syndrome. - Open Question
The most common reason a physician might recommend that a woman have maternal serum screening and a karyotype analysis is concern that her fetus may have Down syndrome. Go to the OMIM website at www.ncbi.nlm.nih.gov/omim and look up Down syndrome (OMIM 190685).
Look at the 'Mapping' and 'Molecular Genetics' sections and describe what is meant by the Down syndrome critical region (DSCR). - Open QuestionWhen cows have twin calves of unlike sex (fraternal twins), the female twin is usually sterile and has masculinized reproductive organs. This calf is referred to as a freemartin. In cows, twins may share a common placenta and thus fetal circulation. Predict why a freemartin develops.
- Open QuestionAn attached-X female fly, XXY (see the 'Insights and Solutions' box), expresses the recessive X-linked white-eye mutation. It is crossed to a male fly that expresses the X-linked recessive miniature-wing mutation. Determine the outcome of this cross in terms of sex, eye color, and wing size of the offspring.
- Open QuestionAssume that on rare occasions the attached X chromosomes in female gametes become unattached. Based on the parental phenotypes in Problem 12, what outcomes in the F₁ generation would indicate that this has occurred during female meiosis?
- Open QuestionWhat is a Barr body, and where is it found in a cell?
- Open QuestionIndicate the expected number of Barr bodies in interphase cells of individuals with Klinefelter syndrome; Turner syndrome; and karyotypes 47,XYY, 47,XXX, and 48,XXXX.
- Open QuestionDrosophila may be monosomic for chromosome 4, yet remain fertile. Contrast the F₁ and F₂ results of the following crosses involving the recessive chromosome 4 trait, bent bristles:monosomic IV, normal bristles x diploid, bent bristles.
- Open QuestionDrosophila may be monosomic for chromosome 4, yet remain fertile. Contrast the F₁ and F₂ results of the following crosses involving the recessive chromosome 4 trait, bent bristles:monosomic IV, bent bristles x diploid, normal bristles
- Open QuestionDefine the Lyon hypothesis.