Exam 15: The Chromosomal Basis of Inheritance

Which of the following is known as a Philadelphia chromosome?

The centimorgan (cM)is a unit named in honor of Thomas Hunt Morgan. To what is it equal?

Down syndrome has a frequency in the U.S. population of ~1/700 live births. In which of the following groups would you expect this frequency to be significantly higher?

Duchenne muscular dystrophy (DMD)is caused by a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition?

In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A recessive lethal allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a normal female?

Sex determination in mammals is due to the SRY region of the Y chromosome. An abnormality of this region could allow which of the following to have a male phenotype?

What is the reason that linked genes are inherited together?

What does a frequency of recombination of 50% indicate?

At what point in cell division is a chromosome lost so that, after fertilization with a normal gamete, the result is an embryo with 45, X? I.an error in anaphase I II.an error in anaphase II III.an error of the first postfertilization mitosis IV.an error in pairing

Mitochondrial DNA is primarily involved in coding for proteins needed for electron transport. Therefore, in which body systems would you expect most mitochondrial gene mutations to be exhibited?

The following is a map of four genes on a chromosome. Figure 15.1 -Between which two genes would you expect the highest frequency of recombination?

Use the following information to answer the questions below. A plantlike organism on the planet Pandora can have three recessive genetic traits: bluish leaves, due to an allele (a) of gene A; a feathered stem, due to an allele (b) of gene B; and hollow roots due to an allele (c) of gene C. The three genes are linked and recombine as follows: A geneticist did a testcross with an organism that had been found to be heterozygous for the three recessive traits and she was able to identify progeny of the following phenotypic distribution (+ = wild type): -If recombination is equal to distance in centimorgans (cM), what is the approximate distance between genes A and B?

In humans, male-pattern baldness is controlled by an autosomal gene that occurs in two allelic forms. Allele Hn determines nonbaldness, and allele Hb determines pattern baldness. In males, because of the presence of testosterone, allele Hb is dominant over Hn. If a man and woman both with genotype HnHb have a son, what is the chance that he will eventually be bald?

Which of the following produces a Mendelian pattern of inheritance?

A nonreciprocal crossover causes which of the following products?

Figure 15.3 -The pedigree in Figure 15.3 shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely

Genomic imprinting is generally due to the addition of methyl (-CH₃)groups to C nucleotides in order to silence a given gene. If this depends on the sex of the parent who transmits the gene, which of the following must be true?

If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?

Which of the following statements is true of linkage?

Figure 15.2 -In a series of mapping experiments, the recombination frequencies for four different linked genes of Drosophila were determined as shown in Figure 15.2. What is the order of these genes on a chromosome map?