What are short tandem repeats (STRs)?

Short tandem repeats (STRs) are characterized as short blocks of DNA sequences typically composed of 1 to 10 base pairs that are repeated multiple times in a row. These sequences can be found in various locations throughout the genome and are particularly useful in genetic studies and forensic analysis due to their high variability among individuals.

The reason why this is the correct choice lies in the definition and functional significance of STRs. They play a critical role in genetic fingerprinting and analysis because the number of repeats can differ significantly between individuals, making them valuable for establishing identity, paternity testing, and understanding genetic diversity in populations.

In contrast, the other choices do not accurately describe STRs. Sequences of 50-100 base pairs that vary among individuals refers to longer repetitive elements or different genetic markers, which are not classified specifically as STRs. Long stretches of non-repeated DNA sequences are not relevant in the context of STRs, which are defined by their repetitive nature. Lastly, while STRs can be found in specific populations, they are not unique genetic markers limited to those populations, but rather shared broadly among individuals within and across different groups. Thus, understanding STRs as short repeated sequences is essential for their application in various fields of molecular diagnostics and