What is an SNP?

An SNP, or single nucleotide polymorphism, refers to a specific type of variation in the DNA sequence where a single nucleotide—an adenine (A), thymine (T), cytosine (C), or guanine (G)—is substituted for another at a particular position in the genome. This variation can occur in coding regions of genes, in non-coding regions, or in regulatory regions that control gene expression.

SNPs are significant in the study of genetics, as they can influence how individuals respond to drugs, susceptibility to environmental factors, and overall genetic diversity. They can also be used as markers in genetic association studies, helping to identify connections between genetic variations and diseases or traits. The presence and frequency of SNPs among different populations can also provide insights into evolutionary biology and human migration patterns.

Other choices do not accurately describe what an SNP is. For instance, a method for evaluating health conditions is broader and not specific to genetic variations. A standard procedure for testing embryos relates to different reproductive technologies, and enzymes used in DNA replication refer to biological molecules facilitating DNA synthesis, which is unrelated to the concept of SNPs. Thus, the understanding of SNPs as single nucleotide variations is essential in genetics and personalized medicine.