Answer: DNA profiling often focuses on STRs, which stands for Single Tandem Repeats. These regions of DNA contain repeated sequences of nucleotides in a tandem arrangement and are highly informative for identifying individuals based on their unique DNA profiles. The correct option is a.
Step-by-step explanation:
1) DNA profiling: DNA profiling, also known as DNA fingerprinting, is a technique used to identify individuals based on their unique DNA characteristics. It is commonly used in forensic investigations, paternity testing, and genetic research.
2) STRs: STRs, or Short Tandem Repeats, are specific regions in DNA where short sequences of nucleotides are repeated multiple times in tandem. These repetitive sequences vary in length between individuals, making them highly informative for DNA profiling purposes.
3) Single Tandem Repeats: The term "Single Tandem Repeats" refers to the fact that each STR region consists of a single repeated sequence unit, which is repeated in a tandem arrangement. For example, an STR region might contain the sequence "AGAT" repeated multiple times, such as "AGATAGATAGAT."
4) Importance in DNA profiling: DNA profiling focuses on STRs because they exhibit high levels of genetic variation within a population. The number of repeats at each STR locus can vary between individuals, creating unique DNA profiles that can be used for identification purposes.
5) Analyzing STRs: In DNA profiling, specific STR loci are selected for analysis. The number of repeats at each STR locus is determined by using polymerase chain reaction (PCR) and capillary electrophoresis techniques. The resulting DNA profile is then compared to known reference samples to determine individual identity or genetic relationships.