Book Viewer

Short Contents | Full Contents | Other books @ NCBI

Modern Genetic Analysis Answers to Selected Problems
Chapter 8*

2. | a. Paracentric inversion b. Deletion c. Pericentric inversion d. Duplication See question

3. | a. The observed RF will be 27%. b. The observed RF will be 36%. See question

5. | See question

6. | The data suggest that one or both breakpoints of the inversion are located within an essential gene, causing a recessive lethal mutation. See question

8.

a. The Sumatra chromosome is a pericentric inversion compared with the Borneo chromosome.
b.
c.
d. Recall that all single crossovers within the inverted region will lead to 50% viable parental types and 50% extremely unbalanced gametes that will most likely be nonviable. In other words, if 30% of the meioses have a crossover in this region, 15% of the gametes will not lead to viable progeny. That means that 85% of the gametes should produce viable progeny.
See question

11.

Cross 1: Independent assortment of the two genes (expected for genes on separate chromosomes).

Cross 2: The two genes now appear to be linked (the observed RF is 1%); additionally, half the progeny are inviable. These data suggest that a reciprocal translocation occurred and both genes are very close to the breakpoints.

Cross 3:The viable spores are of two types: half contain the normal (nontranslocated) and half contain the translocated chromosomes.

See question

15. | Create a hybrid by crossing the two plants and then double the chromosomes with a treatment that disrupts mitosis, such as colchicine treatment. Alternatively, diploid somatic cells from the two plants can be fused and then grown into plants through various culture techniques. See question

16. | (a). 5 wild type (a+):1 a; (b). 1 wild type (a+):1 a; (c). 3 wild type (a+):1 a; (d). 11 wild type (a+):1 a. See question

21.

a. Loss of one X in the developing fetus after the two-cell stage.
b. Nondisjunction leading to Klinefelter syndrome (XXY), followed by a nondisjunctive event in one cell for the Y chromosome after the two-cell stage, resulting in XX and XXYY.
c. Nondisjunction of the X at the one-cell stage.
d. Fused XX and XY zygotes (either from the separate fertilizations of two eggs or an egg and a polar body by one X-bearing and one Y-bearing sperm).
e. Nondisjunction of the X at the two-cell stage or later.
See question

© 1999 by W. H. Freeman and Company. All rights reserved.