Short tandem repeats (STRs)

Definition

Short tandem repeats (STRs) are repetitive sequences of 2 to 6 base pairs of DNA that are found throughout the genome. These sequences are highly variable among individuals, making them useful in various applications, especially in genetic profiling and forensic analysis.

5 Must Know Facts For Your Next Test

1. STRs are commonly used in forensic science because their high variability allows for precise individual identification, even from small or degraded samples.
2. The FBI maintains a database called CODIS (Combined DNA Index System) that utilizes STR profiles for criminal investigations and missing persons cases.
3. Because STRs can be inherited, they can also be used in paternity testing and ancestry research, helping to establish biological relationships.
4. In the human genome, certain STR loci have been identified as highly polymorphic, meaning they exhibit a wide range of repeat numbers among different individuals.
5. Advancements in polymerase chain reaction (PCR) technology have significantly enhanced the ability to amplify and analyze STRs, making them a cornerstone of modern genetic analysis.

Review Questions

• How do short tandem repeats (STRs) contribute to the field of forensic science?
  • STRs play a crucial role in forensic science as they provide highly variable genetic markers that can differentiate between individuals. When DNA samples from crime scenes are analyzed, STR profiling helps create unique genetic profiles that can link suspects to crimes or identify victims. The high degree of variability in STR regions allows forensic analysts to achieve reliable results even from small or degraded samples.
• Discuss the significance of the FBI's CODIS database and its reliance on short tandem repeats (STRs) for criminal investigations.
  • The FBI's CODIS database is significant because it centralizes DNA profiles derived from STR analysis for use in criminal investigations across various jurisdictions. By comparing unknown DNA samples from crime scenes with existing profiles in CODIS, law enforcement can identify potential suspects or link cases together. The reliance on STRs ensures that the profiles are both unique and consistent, facilitating effective collaboration among law enforcement agencies.
• Evaluate the impact of advancements in technology on the analysis of short tandem repeats (STRs) and its implications for future genetic research.
  • Advancements in technology, particularly in PCR and next-generation sequencing, have revolutionized the analysis of STRs by improving sensitivity and accuracy. This has expanded the applications of STR analysis beyond forensics to include fields such as personalized medicine and evolutionary biology. As technology continues to evolve, researchers can expect more precise genetic profiling techniques that may lead to deeper insights into human genetics, population studies, and even disease associations.

Related terms

DNA Profiling: A forensic technique used to identify individuals by analyzing specific regions of their DNA, including STRs, to create a unique genetic profile.

Polymorphism: The occurrence of two or more different alleles at a locus within a population, which contributes to genetic diversity and can include variations in STRs.

Genetic Markers: Specific alleles or DNA sequences used to identify individuals or species, often including STRs as markers due to their variability and ease of analysis.