Final answer:
Sickle cell anemia is an autosomal recessive disorder, requiring two copies of the harmful allele to manifest the disease, while carriers with one copy do not typically show symptoms.
Step-by-step explanation:
The mode of inheritance of sickle cell anemia is autosomal recessive. This means that an individual must inherit two copies of the harmful allele (S), one from each parent, to express the disease. Those who inherit only one copy of the allele (AS) are considered carriers and do not typically show symptoms of the disease; this is known as sickle cell trait.
Sickle cell anemia occurs due to a mutation in the hemoglobin gene, specifically a single base pair change from GAG to GTG, which affects the amino acid sequence in the beta-globin chain of the hemoglobin protein. This mutation causes red blood cells to become sickle or crescent-shaped, leading to complications such as blood vessel blockages, pain, and organ damage.