Final answer:
Inserting a mutation into the SEBI gene results in a defective gene that alters the phenotype. Mutations can cause serious genetic disorders like SCID or alter developmental processes like sex characteristic development.
Step-by-step explanation:
When the SEBI gene is inserted with a mutation, then the gene becomes defective, leading to a certain phenotype. A mutation can significantly alter the function of a gene, which may result in abnormal development or disease states. For instance, a mutation in the SRY protein, which is involved in male sex characteristic development, would result in a lack of these characteristics if the mutation abolished the protein's activity. Similarly, a mutation in the SF1 gene that abolished its activity would also increase the effect of an SRY mutation, making the person more feminine. In the context of genetic disorders, mutations in genes essential for specific bodily functions can lead to a wide range of diseases, such as Severe Combined Immunodeficiency (SCID) and sickle cell anemia.