Final answer:
Electrophoretic analysis might show no difference between normal beta-globin and that from a person with hereditary anemia if the mutation does not significantly change the protein's charge or size, as in the case of sickle cell anemia where a glutamic acid is substituted by a valine.
Step-by-step explanation:
Electrophoretic analysis of beta-globin can reveal no difference in electrophoretic mobility between a normal person and a person with hereditary anemia if the mutation does not affect the overall charge or size of the beta-globin protein. The principle behind electrophoresis is that it separates proteins based on their charge and size. In conditions such as sickle cell anemia, there is a single amino acid substitution in the beta-globin chain. This change may not alter the overall charge or the size enough to be detected on an electrophoresis gel. In sickle cell anemia, the amino acid glutamic acid is replaced with valine, which does not contribute a significant change in net charge. Therefore, it could result in the beta-globin of a normal individual and a person with sickle cell anemia migrating the same distance through the gel, leading to the observation that there is no apparent difference in their electrophoretic mobility.
The mutation in the beta-globin gene that causes sickle cell anemia changes the DNA sequence from CCTGAGG to CCTGTGG, eliminating a restriction site for endonuclease Cvn-1, which would otherwise cut the DNA at that sequence. Thus, DNA electrophoresis (which separates fragments based on size) will show a difference, but protein electrophoresis (which focuses on charge and size of the protein) may not reflect this change if the mutation does not significantly alter the properties of the protein that affect its movement in an electric field.