Exam 13: Genes, Chromosomes, and Human Genetics

The presence of genes that encode many types of hemoglobin in mammals, but not in other vertebrates that evolved earlier, is evidence of ____ of genetic material. ​

About 10-15% of African Americans in the US are carriers for ____, an autosomal recessive genetic disorder in which a defective version of the hemoglobin protein is produced. ​

An autosome is a ____. ​

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 ____.

During normal human embryonic development, if ____, then the SRY gene switches development toward ____. ​

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.

If a hypothetical human female of genotype XX had no Barr body in any of her cells, ---____. ​

Figure 13.4 The change in the chromosome depicted between the top and the bottom in the accompanying figure represents a(n)____.

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. The woman has an X-linked recessive form of hemophilia, but the man does not. How should you advise them?

In humans, an extra copy of chromosome 21 typically leads to moderate to severe mental retardation and sterility, as well as to a greater likelihood of heart defects and other problems. This disorder is known as ____.

Suppose that you have discovered a new mutant in Drosophila melanogaster . The trait is known to be sex linked. Which crosses should you perform to determine if the mutant trait is recessive or dominant?

About 4% of individuals of Northern European descent are carriers for ____, an autosomal recessive genetic disorder in which a defective membrane transport protein leads to deficient chloride levels in extracellular fluids. ​

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

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? ​

Chemical compounds released during tobacco use can cause ____.

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 cystic fibrosis. Genetic tests reveal that the woman is a carrier for cystic fibrosis but the man is not. How should you advise them? ​