Genetics: Analysis and Principles 4th Edition by Robert Brooker

Exercise 5

A human gene called the -globin gene encodes a polypeptide that functions as a subunit of the protein known as hemoglobin. Hemoglobin is found within red blood cells; it carries oxygen. In human populations, the -globin gene can be found as the common allele called the Hb A allele, but it can also be found as the Hb S allele. Individuals who have two copies of the Hb S allele have the disease called sickle cell disease. Are the following examples a description of genetics at the molecular, cellular, organism, or population level
A. The Hb S allele encodes a polypeptide that functions slightly differently from the polypeptide encoded by the Hb A allele.
B. If an individual has two copies of the Hb S allele, that person's red blood cells take on a sickle shape.
C. Individuals who have two copies of the Hb A allele do not have sickle cell disease, but they are not resistant to malaria. People who have one Hb A allele and one Hb S allele do not have sickle cell disease, and they are resistant to malaria. People who have two copies of the Hb S allele have sickle cell disease, and this disease may significantly shorten their lives.
D. Individuals with sickle cell disease have anemia because their red blood cells are easily destroyed by the body.