Here we have tried to answer the most common and frequently asked questions that we get from our clients. If you have a question that isn’t answered here, feel free to leave us a comment or email us at [email protected]. We’re here to help you answer some of life’s most important questions.
Q: WHAT IS DNA? PART 1: HUMAN DNA & THE SCIENTIFIC BASICS
A: We’ve all heard of ‘DNA’, and we know that we have DNA in our body, but what really is DNA? As a basic scientific definition, DNA stands for deoxyribonucleic acid, and is the building block for a chromosome. Each chromosome is made up of a pair of DNA strands and is located in the nucleus of each cell in our body. Each strand of DNA is made up of smaller protein molecules, called nucleotides, more commonly known as base molecules, or bases for short. There are four (4) bases – adenine (A), cytosine (C), guanine (G), and thymine (T). The two strands of DNA are linked together at each base by hydrogen bonds. This pair of DNA strands twist around a central axis to give the special double helix shape with which we are all so familiar.
The DNA strands wrap around a group of eight histone protein molecules, creating a large ball-shaped structure, called a nucleosome. These nucleosomes arrange themselves into a helical shape, similar to a bungee telephone cord, in order to be as compact as possible. This helical strand is compacted even further by ‘supercoiling’ and overall forms a single rod-shaped structure called a chromatin.
Just before cell division, the chromosome makes an exact copy of itself and turns into that characteristic ‘H’ shape. The chromosome is now made up of two identical chromatids joined at a point called the centromere.
Chromosomes in Paternity Testing
Humans have 23 pairs of chromosomes, with 23 chromosomes inherited from the father and the other 23 from the mother. Together, these chromosomes hold all the information necessary for the construction and maintenance an individual human being – like a special recipe book to create every protein needed by our body to grow and repair itself.
Each set of 23 chromosomes combined have three billion base pairs that contain roughly 23,000 protein coding genes. A gene is a distinct length of base pairs on a DNA molecule. A locus (plural = loci) is the location at which a gene can be found.