Question

In Central Africa, the frequency (percent) of the sickle cell gene, compared to the normal gene, has remained stable over the years because the sickle cell gene protects against malaria. You can view a video about this here. In the United States, malaria was eradicated shortly before World War II by eliminating the mosquito that spreads the disease. What has likely happened to the frequency of the sickle cell gene in African-Americans living in the United States since the elimination of malaria?

a. The normal gene has disappeared from the African American population.
b. The frequency of the sickle cell gene has not changed during this time period.
c. The sickle cell gene has disappeared from the African American population.
d. The frequency of the sickle gene has decreased.
e. The frequency of the sickle cell gene has increased.

Answer 1

The frequency of the sickle cell gene in African-Americans has likely decreased since the eradication of malaria in the United States, as the gene's protective advantage against malaria is no longer needed, and it can lead to health issues. The correct option is a.

Step-by-step explanation:

Since the elimination of malaria in the United States, the frequency of the sickle cell gene in African-Americans is likely to have decreased. This is because the protective advantage against malaria is no longer relevant in an area where the disease is not prevalent.

Without malaria, those with the sickle cell gene who are homozygous (have two copies) tend to suffer more frequent and severe episodes of the disease, while heterozygous individuals (with one sickle cell gene) experience minor health problems.

These health issues can reduce the overall "fitness" of individuals carrying the sickle cell gene, leading to a potential decrease in the frequency of the gene over time. The correct option is a.