Nuclear DNA

Nuclear deoxyribonucleic acid, or nuclear DNA (nDNA) as it is more commonly referred to, is the DNA that is found in the nucleus of eukaryotic organisms, including human beings. Nuclear DNA is the most common type of DNA used in forensic excavations.

Nuclear DNA is found in the nucleus of cells, the small cell structure or organelle, which is responsible for organizing genes into chromosomes for cell division, which is imperative to cell growth and repair. It also forms the packaging for genes, among other important functions. In addition, nuclear DNA generally encodes a larger part of the genome than mitochondrial DNA. The genome is the total hereditary information of the individual that is encoded into DNA, which includes genes and non-coding DNA sequences, DNA whose specific function has not yet been identified.

Unlike mitochondrial DNA (mtDNA), nuclear DNA is passed on sexually as opposed to matrilineally, meaning that this type of DNA is inherited from both the individual’s biological mother and father. This is in contrast to mitochondrial DNA, to which only the mother contributes.

However, nuclear DNA is not an exact replication of the DNA of the individual’s parents, but rather a mixing of their nuclear DNA. As a result, some of the individual’s chromosomes—the microscopic organelles found inside of the cells that carry DNA—will be similar to that of the individual’s parents. On the other hand, some of the individual’s chromosomes will have experienced crossing over during meiosis, thereby resulting in mixed chromosomes. Meiosis is the stage during which two-part cell division occurs in organisms that reproduce sexually. During this stage, cell division results in gametes that have half the number of chromosomes of the parent cell.

Therefore, unlike mitochondrial DNA, which is an exact replica of the DNA of the individual’s mother, nuclear DNA does not provide a genetic profile that establishes a direct link between an individual and his parents. This makes nuclear DNA a less clear-cut tool in establishing the biological relationships between the remains found of different individuals in archaeological excavations. In addition, nuclear DNA is more difficult to obtain than mtDNA, because nuclear DNA is found in lower quantities. As a result, mtDNA is preferred to nuclear DNA when conducting DNA analysis of ancient human remains discovered during archaeological excavations, because it provides experts with a higher level of accuracy when creating an individual’s DNA profile and when comparing this profile to those of potential relations.