Exam 13: Genes, Chromosomes, and Human Genetics

Figure 13.5 The change in the chromosome depicted between the top and the bottom in the accompanying figure represents a(n) ____.

It has been known for some time that fetal cells can be found in a pregnant woman's bloodstream, sometimes years after a pregnancy. A new technique has been developed that allows scientists to isolate these fetal cells from a pregnant woman's blood. Why would this be a useful new tool for parents interested in genetic testing of their fetus?

Figure 13.3 The change in the chromosomes depicted between the top and the bottom in the accompanying figure represents a(n) ____.

About half of all flowering plant species, including many important crop plants, are ____.

In placental mammals, such as humans, the dosage compensation mechanism to equalize expression of sex-linked genes in males and females involves ____.

In Drosophila melanogaster, the allele for red eyes is dominant over the allele for purple eyes, and the allele for a gray body is dominant over the allele for a black body. A testcross was done to check for genetic linkage between the genes for these traits. The results for the offspring are listed as follows: 478 flies with red eyes and a gray body 27 flies with red eyes and a black body 462 flies with purple eyes and a black body 33 flies with purple eyes and a gray body Which of the choices below best represents the map distance between the genes for these two traits?

The map distances for four linked genes are as follows: A is 22 cM from B, B is 7 cM from C, C is 9 cM from D, B is 2 cM from D, A is 20 cM from D, and A is 29 cM from C. Based on these data, what is the order of these four genes on the chromosome?

Figure 13.6 The change in the chromosome depicted between the top and the bottom in the accompanying figure represents a(n) ____.

In birds and butterflies, males contain ____ sex chromosomes and females contain ____ sex chromosomes.

Exceptions to the principle of independent assortment were discovered and explained by ____ as resulting from genes being physically associated with each other on the same chromosome.

Suppose that in studies of genes on the same chromosome you find the following recombination frequencies: Figure 13.1 In this case, it would be proper to say that a , c , and b are ____.

Genetic studies of an animal show that eye color is controlled by an autosomal gene with the dominant allele ( R ) for red eye color and the recessive allele ( r ) for yellow eye color. A second autosomal gene has the dominant allele ( T ) for paws with thumbs and the recessive allele ( t ) for paws without thumbs. The genetic cross RRTT x rrtt creates offspring with genotype RrTt . One of those dihybrids is mated in a testcross ( RrTt x rrtt ). Based on the principle of independent assortment, the testcross should produce offspring with the phenotype ratio ____.

Figure 13.6 Examine the pedigree in the accompanying figure. Individuals affected by the genetic condition in question are indicated by filled squares or circles. Which inheritance pattern is most likely correct for this condition in this family?

In cells of human individuals with three or more X chromosomes, ____.

You are a genetic counselor, and a couple comes to you with concerns that if they have a child together, he or she could have hemophilia. Neither of them has hemophilia, but the woman's biological father did have an X-linked recessive form of hemophilia. How should you advise them?

Which is most likely to happen to a human polyploid?

A certain genetic disorder appears to be inherited from mother to child. What are two possible modes of inheritance for this disorder?

Most hospitals in the United States routinely test all newborns for ____, an autosomal recessive disorder in which a metabolic abnormality causes a buildup of compounds that damage brain tissue and can lead to mental retardation, unless a restricted diet is followed.

Individuals with three or more copies of each of their chromosomes are called ____.

Two genes are on the same chromosome, yet crossing-over occurs between them every time meiosis occurs. Are these genes linked or unlinked and why?