Question

An individual's set of unique __________ can be used as a DNA profile. a. DNA sequences c. SNPs b. short tandem repeats d. all of the above

Short answer

d. all of the above

Step-by-step solution

Understanding DNA Profiling

DNA profiling involves analyzing sections of DNA that vary from person to person to differentiate between individuals. These variations make it possible to create a unique DNA profile for each person.

Identify the DNA Features

Identify and understand the terms provided in the options: DNA sequences, single nucleotide polymorphisms (SNPs), and short tandem repeats (STRs). STRs are repetitive sequences in the DNA that are highly variable between individuals, making them very useful for DNA profiling.

Evaluate the Role of Each Option

Determine whether each feature can be used to create a DNA profile. While all options represent parts of DNA, STRs are specifically used for DNA profiling due to their high variability among individuals. SNPs can also be used for DNA profiling, but STRs are the traditional basis for forensic profiles.

Choosing the Correct Answer

Compare each option in terms of relevance to DNA profiling. "All of the above" includes all possible features that might be useful in constructing a DNA profile. Traditional DNA profiling heavily relies on STRs, while newer methods may incorporate SNPs and even full DNA sequences.

Key concepts

Short Tandem Repeats (STRs)

Short tandem repeats, or STRs, are repetitive sequences in our DNA where the same sequence of two to six nucleotides is repeated multiple times in a row. These repeats are found at specific locations in our genome and are highly variable among different individuals, making them an excellent tool for DNA profiling.

The number of times a sequence is repeated can vary significantly from person to person. That's why these STRs offer a high degree of variability that can help distinguish one individual’s DNA from another's, which is why they are traditionally used in forensic investigations to create DNA profiles. STR analysis is so effective in identifying individuals that it is a standard method in legal settings, including crime scene investigations, paternity testing, and identifying missing persons.

In forensic labs, scientists often analyze multiple STR loci at once to create a more comprehensive DNA profile. This is because analyzing several loci increases the discriminative power, ensuring the DNA profile is uniquely tied to an individual. As a quick visual analogy, imagine a barcode that is specific to each person. STR-driven profiles are akin to this unique barcode, composed from multiple STR markers.

Single Nucleotide Polymorphisms (SNPs)

Single nucleotide polymorphisms, or SNPs (pronounced "snips"), are the most common type of genetic variation among people. Each SNP represents a difference in a single nucleotide and occurs on average once every 300 nucleotides across the human genome. This means that there are roughly 10 million SNPs in the human genome.

SNPs can function as biological markers, helping scientists locate genes associated with disease. They are also becoming increasingly popular in DNA profiling, given that they provide unique genetic information that can distinguish individuals. While STRs were primarily used in traditional forensic analysis, SNPs represent the future frontier, allowing for more comprehensive genetic data to be gathered and used in profiling due to their abundance and ease of analysis with modern technology.

Moreover, because some SNPs are associated with specific traits or conditions, their applications extend beyond simple identification. For instance, SNP analysis is progressively being utilized in personalized medicine, helping to tailor treatments to an individual based on genetic predispositions.

DNA Sequences

DNA sequences are the precise order of nucleotides within a DNA molecule. These sequences are composed of the four nucleotide bases: adenine (A), cytosine (C), guanine (G), and thymine (T). Understanding the order of these bases is crucial as it encodes the biological instructions that govern the development and functioning of all living organisms.

In the context of DNA profiling, the entire DNA sequence of an individual could potentially offer a wealth of information for identification purposes. However, due to the sheer length and complexity of human DNA, complete sequencing is not typically used for profiling. Instead, focused sequencing of specific regions like STRs or SNPs offers a more efficient approach to differentiate individuals.

Despite this, advancements in sequencing technology are gradually making it possible to consider wider applications. Not limited to forensic analysis, complete DNA sequencing can assist in understanding genetic diseases, decoding evolutionary histories, and exploring the biodiversity of our planet. It's the foundational template of life, and cracking open its sequences can unlock a deeper understanding of our own biology.