Download Ditto Chapter 15 Chromosomes

Chapter 15: The Chromosomal Basis of Inheritance
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Date_______
1. A man with hemophilia (a recessive, sex linked condition) has a daughter of normal
phenotype. She marries a man who is normal for the trait.
a. What is the probability that a daughter of this mating will be a hemophiliac?
b. That a son will be a hemophiliac?
c.
If the couple has four sons, what is the probability that all four will be born with
hemophilia?
2. Pseudohypertrophic muscular dystrophy is a disorder causing gradual deterioration of the
muscles. It is seen only in boys born to apparently normal parents & usually results in
death in the early teens.
a. Is this disorder caused by a dominant or recessive allele?
b. Is its inheritance sex-linked or autosomal?
c.
Explain why this disorder is seen almost entirely in boys and rarely in girls.
3. Red-green color blindness is caused by a sex-linked recessive allele. A color blind man
marries a woman with normal vision whose father was color blind.
a. What is the probability that they will have a color blind daughter?
b. What is the probability that their first son will be color blind?
4. A wild type fruit fly (heterozygous for gray body color & normal wings) was mated with a
black fly with vestigial wings. The 1883 offspring had the following phenotypic distribution:
wild type: 778
black-vestigial: 785
black-normal wing: 158
gray-vestigial wing: 162
What is the recombination frequency between these genes for body color & wing type?
Chapter 15: The Chromosomal Basis of Inheritance
5. What pattern of inheritance would lead a geneticist to suspect that an inherited disorder of
cell metabolism is due to a defective mitochondrial gene?
6. An aneuploid person is obviously female, but her cells have two Barr bodies. What is the
probable complement of sex chromosomes in this individual?
7. Draw a gene map to determine the sequence of genes along a chromosome based on the
following recombination frequencies: (Think !!)
genes A-B: 8 map units apart
genes A-C: 28 map units apart
genes A-D: 25 map units apart
genes B-C: 20 map units apart
genes B-D 33 map units apart
8. About 5% of individuals with Down Syndrome are the result of a chromosomal
translocation in which one copy of chromosome 21 becomes attached to chromosome 14
during meiosis. How does this differ from "conventional" Down Syndrome.
9. More common than completely polyploid animals are mosaic polyploids, animals that are
diploid except for patches of polyploid cells. How might a mosaic tetraploid- an animal
with some cells containing four sets of chromosomes- arise from an error in mitosis?
10. In Drosophila, the gene for white eyes and the gene that produces “hairy” wings have both
been mapped to the same chromosome and have a crossover frequency of 1.5%. A
geneticist noticed that in a particular stock of flies, these two genes assorted
independently; that is, these two genes behaved as though they were on different
chromosomes. What explanation can you offer for this observation?
Chapter 15: The Chromosomal Basis of Inheritance
11. ______________ segregate during ___________.
a. Homologues; mitosis
b. Genes on one chromosome; meiosis
c. Homologues; meiosis
d. Genes on one chromosome; mitosis
12. The probability of a crossover occurring between two genes on the same chromosome is
a. unrelated to the distance between them
b. increased if they are closer together on the chromosome
c. increased if they are farther apart on the chromosome
d. impossible
13. Chromosome structure can be altered by
a. deletions
b. duplications
c. inversions
d. translocations
e. all of the above
14. Nondisjunction can be caused by
a. crossing over in mitosis
b. segregation in meiosis
c. failure of chromosomes to separate during meiosis
d. multiple independent assortment
15. A gamete affected by nondisjunction would have
a. a change from the normal chromosome number
b. one extra or missing chromosome
c. the potential for a genetic disorder
d. all of the above
16. Genetic disorders can be caused by
a. altered chromosome number
b. altered chromosome structure
c. mutation
d. all of the above
17. Which of the following events contributes to phenotypic variation in a population?
a. independent assortment
b. crossing over
c. changes in chromosome structure and number
d. all of the above
Matching:
18. crossing over
19. deletion
20. nondisjunction
21. translocation
22. karyotype
a. number and defining features of
individual’s metaphase chromosomes
b. chromosome segment moves to a
nonhomologous chromosome
c. disrupts gene linkages at meiosis
d. causes gametes to have abnormal
chromosome numbers
e. loss of a chromosome segment
Chapter 15: The Chromosomal Basis of Inheritance
23. DNA is present in
a. ribosomes
b. nuclei
c. mitochondria
d. both b and c
24. Mitochondrial genes are passed on to offspring from the
a. father
b. mother
c. grandparents
d. both parents
25. A disorder which is always passed on from mother to son is considered
a. autosomal
b. trisomic
c. X linked
d. Y linked
26. The hairy ears (known as “hairy pinnae”) disorder is passed on from father to son.
This disorder is
a. X linked
b. Y linked
c. autosomal
d. trisomic
27. Trisomy 21 is
a. 3 homologous chromosomes of chromosome 21
b. Down syndrome
c. an aneuploid disorder
d. a condition caused by nondisjunction
e. all of the above