What are Short Tandem Repeats (STRs) used for in genetic testing?

Short Tandem Repeats (STRs) are commonly used in genetic testing principally for their ability to serve as genetic markers. STRs are repetitive sequences of DNA that occur in specific locations throughout the genome, and the number of repeat units can vary among individuals. This variability is what makes STRs particularly useful for identification purposes, as each person's STR profile is unique, much like a fingerprint.

In the context of genetic testing, STRs can be used in various applications, such as forensic analysis, paternity testing, and population genetics. By comparing the patterns and lengths of STRs among different individuals, it is possible to determine familial relationships or to link DNA samples to a specific person in forensic cases.

The other options reflect different aspects of genetic analysis that do not align with the primary role of STRs. For instance, sequencing entire genes involves determining the exact order of nucleotides within a gene, which is not the function of STRs. Analyzing protein structures pertains to understanding how proteins fold and interact, which is beyond the scope of what STRs represent. Measuring gene function involves examining how genes express themselves and their roles in biological processes, a topic not directly related to the repetitive nature of STRs.