Final answer:
Sickle cell trait is characterized by having one normal hemoglobin gene and one mutated gene, resulting in normal red blood cell production and typically no severe symptoms like those seen in sickle cell anemia.
Step-by-step explanation:
The other characteristic of sickle cell trait is normal red blood cell production. Individuals with sickle cell trait have one normal hemoglobin gene and one mutated gene. This means they produce both normal hemoglobin (A) and sickle cell hemoglobin (S), but in most circumstances, they maintain a normal amount of red blood cells because the majority of the hemoglobin within the cells is normal. They generally do not exhibit the severe symptoms associated with sickle cell anemia, which occurs in individuals who inherit two sickle cell genes and produce only hemoglobin S. However, during extreme conditions such as low oxygen levels, dehydration, or high altitude, some of their red blood cells can sickle but to a lesser degree than those with sickle cell anemia.