Are SNPs located just on genes?

Are SNPs located just on genes?

• A. They are located on mitochondria
• B. They are located only on genes
• C. They occur only in noncoding DNA
• D. They are located throughout the chromosome

Answer: (D)

Single nucleotide polymorphisms are single-base changes that can occur anywhere in the DNA, not just inside gene bodies. They exist in coding regions (exons) where they can alter amino acid sequences, in introns and regulatory elements, and in the large amounts of noncoding DNA between genes. They also occur in the mitochondrial genome. Because SNPs can be found across the entire genome, the description that they are located throughout the chromosome best captures this distribution. The other statements are too restrictive: SNPs are not limited to mitochondria, not limited to genes, and not limited to noncoding DNA.

Single nucleotide polymorphisms are single-base changes that can occur anywhere in the DNA, not just inside gene bodies. They exist in coding regions (exons) where they can alter amino acid sequences, in introns and regulatory elements, and in the large amounts of noncoding DNA between genes. They also occur in the mitochondrial genome. Because SNPs can be found across the entire genome, the description that they are located throughout the chromosome best captures this distribution. The other statements are too restrictive: SNPs are not limited to mitochondria, not limited to genes, and not limited to noncoding DNA.