Question

Fill in the Punnett square below to visualize the offspring of a cystic fibrosis carrier and a person who doesn't have cystic fibrosis and isn't a carrier. Use F to denote the normal allele and f to denote the mutated CFR allele. What percentage of their children are likely to have cystic fibrosis? What percentage of their children are likely to be carriers of cystic fibrosis?

Answer 1

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

Step-by-step explanation:

trust me thats all the answer u need for exercise 4

Answer 2

50% of their children are likely to be carriers of cystic fibrosis

Step-by-step explanation:

Since the normal allele "F" will be the dominant allele while the mutated CFR allele "f" will be the recessive allele, the gene (pair of alleles) of the person that is a CFR carrier will be "Ff" while that of the normal person who isn't a carrier will be "FF". The attachment shows the crossing between the two parents. From the illustration in the attachment, for every 4 children given birth to, 2 of them will likely be normal, "FF", (not a carrier and doesn't have cystic fibrosis) while 2 others will likely be carriers of cystic fibrosis (Ff). Hence, 50% of their children are likely to be carriers of cystic fibrosis.