Which of the following characteristics of short tandem repeats (STRs) makes it useful for DNA fingerprinting?

• A. The number of repeats is highly variable from person to person or organism to organism.
• B. The sequence of DNA that is repeated varies significantly from individual to individual.
• C. The sequence variation is acted upon differently by natural selection in different environments.
• D. Every racial and ethnic group has inherited a specific number of short tandem repeats.

Answer: (A)

Verified step by step guidance

1. Understand the concept of Short Tandem Repeats (STRs): STRs are short sequences of DNA, typically 2-6 base pairs long, that are repeated in a head-tail manner. They are found in various locations in the genome.
2. Recognize the significance of STRs in DNA fingerprinting: STRs are highly polymorphic, meaning the number of repeat units can vary greatly among individuals. This variability makes them useful for distinguishing between individuals in forensic analysis.
3. Consider the variability of STRs: The key characteristic that makes STRs useful for DNA fingerprinting is that the number of repeats is highly variable from person to person. This variability allows for the creation of a unique DNA profile for each individual.
4. Evaluate the options given: The correct answer is the one that highlights the variability in the number of repeats among individuals, as this is the primary reason STRs are used in DNA fingerprinting.
5. Conclude by identifying the correct characteristic: The correct characteristic of STRs that makes them useful for DNA fingerprinting is that the number of repeats is highly variable from person to person or organism to organism.