Nuclear DNA
Definition
The approximately 3.2 billion base pairs of DNA contained in the nucleus of most human cells, organised across 23 pairs of chromosomes. The primary source of individual-specific genetic profiles in forensic typing because each person's combination of alleles at profiled loci is statistically unique.
- Approximate size
- 3.2 billion base pairs
- Location
- Cell nucleus
- Organisation
- 23 pairs of chromosomes
- Forensic role
- Basis of individual-specific STR profiling
Common questions
How does nuclear DNA differ from mitochondrial DNA in forensic use?+
Nuclear DNA is inherited from both parents and gives a highly individualising profile at STR loci, while mitochondrial DNA is maternally inherited, shared identically among maternal relatives, and mainly used when nuclear DNA is too degraded to type, such as in old skeletal remains or hair shafts.
Why can nuclear DNA sometimes fail to yield a usable profile?+
It is present in far fewer copies per cell than mitochondrial DNA, so in highly degraded, aged, or trace samples it can fall below the amount needed for reliable STR amplification, which is when analysts turn to mitochondrial or other alternative methods.
Related terms
- Biological Evidence
- Any material of biological origin recovered in a forensic context that can yield information relevant to an investigation. Includes blood, semen, saliva,...
- Chain of Custody
- The documented chronological record of who collected, handled, transferred, and examined a piece of evidence. For digital evidence, chain of custody includes...
- Degradation
- The breakdown of DNA by enzymatic, chemical, or physical processes after biological material is deposited. Degradation produces fragmented DNA that may not...
- Mitochondrial DNA (mtDNA)
- DNA located in mitochondria rather than the cell nucleus. Present in hundreds to thousands of copies per cell, making it recoverable from...
- Touch DNA
- Minute quantities of epithelial cells transferred by skin contact with a surface, without leaving a visible stain. Collected by swabbing contact points...