What characterizes a Single Nucleotide Polymorphism (SNP)?

A Single Nucleotide Polymorphism (SNP) is characterized by a variation at a single nucleotide position in the DNA sequence among individuals. Specifically, a SNP must occur in greater than 1% of the population to be considered a polymorphism rather than a mutation, meaning that it is common enough to contribute to genetic diversity within a population. SNPs can occur in coding or non-coding regions and may affect gene function or expression, although many SNPs may have no significant impact on phenotype.

The other options highlight characteristics that do not apply to SNPs. The first option refers to deletions, which involve the loss of segments of DNA and are distinct from single nucleotide changes. The second option incorrectly states that SNPs are present in less than 1% of the population, which contradicts the essential definition of a SNP. Lastly, large chromosomal rearrangements involve larger sections of DNA than single nucleotides and encompass different types of genomic variations, such as insertions, deletions, duplications, or inversions, which are not classified as SNPs.