Question

Cystic fibrosis is the most common lethal genetic disorder in Caucasians. Individuals who are homozygous recessive for this trait have a defect of a membrane transporter protein. As a result, they have alterations in amounts of body fluids such as sweat and mucus; thickened mucus often leads to fatal lung infections. When scientists see that a fatal disorder is present in a population at a relatively high frequency, they suspect that there may be some benefit to the genes present. This benefit is called: Group of answer choices

Answer 1

Answer:

1a. The highest rates of cystic fibrosis are seen in Europe, North America, and Australia.

1b. This is because Caucasians of European descent have a higher frequency of the mutated allele that causes cystic fibrosis.

2. Cystic fibrosis is a recessive genetic disorder. An ion channel doesn't function properly, causing cystic fibrosis patients to have thick, sticky mucus. This causes respiratory infections and problems with digestive enzymes reaching the digestive tract, among other health issues.

3. Cystic fibrosis carriers are better protected against cholera and other gastrointestinal diseases, so over time, cholera epidemics have selected for cystic fibrosis carriers. These carriers lived long enough to pass their mutated gene along to future generations.

4. The cystic fibrosis carrier has genotype Ff and the person without the disease has genotype FF.

None of their children would have cystic fibrosis (0%). This is because none of the genotypes in the square are ff.

Half of their children would be carriers of the disease (50%). Carrier means they have the genotype Ff.

 F F

F FF FF

f Ff Ff

5. A cystic fibrosis carrier has genotype Ff.

About one-quarter of their children would be unaffected by cystic fibrosis (25%). The unaffected genotype is FF.

 F f

F FF Ff

f Ff ff

(Exercises 3.1)

Explanation:

Answer 2

Answer:

heterozygote advantage

Explanation:

An heterozygote advantage is when a heterozygous genotype has a greater aptitude than homozygous genotypes. The specific case of heterozygous advantage over a single locus is known as overdominance. In short, this happens when a disorder is present in a heterozygous population, but this disorder has a great benefit for the genes present in the body.