Nucleotide
Nucleotides are the types of molecules that form and comprise the structure of DNA. A nucleotide contains the deoxyribose sugar that is a core component of DNA, as well as phosphate groups, and has a nitrogen base. The sequence of nucleotides and their make-up is what creates the strands of DNA. The ‘backbone’ of DNA is the sugars and phosphate groups, which lie anti-parallel to each other. These sugars are then joined together by a sequence of ‘bases’ which hold the DNA together. The sequence itself is the aspect of DNA that holds and forms information. It is therefore possible to discover the genealogy of humans or other organisms by looking at the nucleotide sequences that are present in their DNA. When DNA samples are compared in this way, scientists can establish whether there is a historical link between generations.
Each person has their own slight difference in DNA construction of nucleotides (called your ‘genotype’), but generally it is possible to trace links in genealogy as the differences only ever amount to around 0.0.1% in the overall sequence. However this small difference can account for, and explain, differences that exist between people overall.
Whilst each person necessitates their own genotype, when variations exist they are often capable of isolation and can be used to identify or explain a pattern of genetic diseases or anomalies in a family or race of organisms. However, it is difficult to establish what specific illnesses are caused by specific variations; it is only really possible to identify a difference. Identical twins are the only people who display no normal difference in genotype.
