Sickle-cell anemia is an example of codominance. what implications does this have for people with one or two copies of the sickle-cell gene?  
            a.  people with two copies of the mutated gene have sickle-cell anemia. people with one copy of the mutated gene have healthy red blood cells.    b.  people with two copies of the mutated gene are carriers of the disease. people with one copy of the mutated gene don't have the disease.    c.  people with two copies of the mutated gene have healthy red blood cells. people with one copy of the mutated gene don't have the disease but are carriers of the disease.    d.  people with two copies of the mutated gene have sickle-cell anemia. people with one copy of the mutated gene have both healthy and misshapen red blood cells and are carriers of the disease. 

D. People with two copies of the mutated gene have sickle-cell anemia. People with one copy of the mutated gene have both healthy and misshapen red blood cells and are carriers of the disease.

Explanation:

Sickle cell anemia is a genetic and hereditary disease, prevalent in blacks, but may also manifest in whites. It is characterized by a change in red blood cells, which lose their round and elastic shape, acquire the appearance of a sickle (hence the sickle cell name) and harden, which makes it difficult for blood to pass through small vessels and oxygenate tissues. .

Sickle cell red cells contain a type of hemoglobin, hemoglobin S, which crystallizes in the lack of oxygen, forming thrombi that block blood flow because they lack the malleability of normal red blood cells.

Sickle cell anemia is caused by genetic mutation, responsible for the deformity of red blood cells. To be a carrier of the disease, the altered gene must be transmitted by the father and the mother. If transmitted only by one parent, the child will have the sickle cell trait, which may pass on to his descendants, but not the manifest illness. Accordingly, we can conclude that people with two copies of the mutated gene (ie, feared the defective hand and father gene) have sickle cell anemia, although the disease does not manifest itself. On the other hand, people with a copy of the mutated gene have healthy and deformed red blood cells and are carriers of the disease.