Altering Primary Protein Structure

Practice: True or false: The following proteins with identical composition are certain to have the same shape/function.

Protein #1: L-G-T-V-R-D                        Protein # 2: D-R-V-T-G-L

Practice: Which amino acid is least likely to alter protein shape/function if substituted with an Arg residue?

Practice: Patients with sickle-cell anemia disease have a point mutation leading to a single amino acid substitution in the hemoglobin protein, causing it to alter its shape/function. Which amino acid substitution most likely causes the disease?