What is DNA and nucleotides?
DNA (deoxyribonucleic acid) is the organic molecule that stores the information that allows the synthesis of all the components of the organism. It could be likened to the organism’s manufacturing manual. In the human species, most of the DNA is found inside the cell nucleus. With exceptions such as red blood cells, all the cells of the organism carry the same DNA, and the differences between cell groups are due to the regions of this information that they encode and read. It is also responsible for hereditary transmission, i.e., the traits and characteristics that individuals pass on to their offspring.
This is what makes it possible to study the DNA of the whole individual from cells found in saliva. It also allows predispositions to traits or diseases in other blood relatives to be determined from one individual.
Nucleotides are the molecules that make up DNA. DNA is a polymer of nucleotides, a chain of nucleotides forming the famous double helix. There are four types of nucleotides in DNA: adenine, cytosine, thymine and guanine. Depending on the order of these four nucleotides, the information they transmit to the cell is different. If DNA is the manufacturing manual, the nucleotides are the letters in which the manual is written.
SNPs are precisely changes in one nucleotide for a different one, for example, changing an adenine for a thymine in the DNA chain.