What is the primary purpose of polyacrylamide gel electrophoresis (PAGE)?

The primary purpose of polyacrylamide gel electrophoresis (PAGE) is to compare the molecular size or charge of proteins. This technique allows researchers to separate proteins based on their size as they migrate through a polyacrylamide gel matrix when an electric current is applied. Smaller proteins move more easily through the gel and thus migrate further compared to larger proteins.

PAGE is particularly useful in various applications, including assessing the purity of a protein sample, studying protein-protein interactions, and analyzing post-translational modifications. The separation of proteins based on their molecular weight can also provide essential insights into their structural and functional characteristics. This differentiation is crucial in fields such as biochemistry, molecular biology, and clinical diagnostics.

The other options do not accurately reflect the primary function of PAGE. For instance, analyzing the shape of macromolecules generally requires different techniques, and while PAGE can provide some indirect information related to protein structure, it's primarily focused on size and charge. Amplifying DNA samples pertains to techniques like polymerase chain reaction (PCR), which is distinctly different from electrophoresis. Identifying genetic mutations usually involves methods like sequencing or specific mutation detection techniques, rather than the general protein separation capabilities of PAGE.