Genealogy and genetics have become very connected to each other. Consider, for example, the various DNA test kits that a genealogist can take to learn more about their heritage or health. The results are based on what is found in the person’s DNA. This could leave some people with an important question. How does DNA work?
DNA stands for deoxyribonucleic acid. Almost every cell in a person’s body has the same DNA. Most DNA is contained in the nucleus of the cell (where it is called nuclear DNA). Some DNA can be in the cell’s mitochondria (where it is called mitochondrial DNA or mtDNA).
DNA is built up from base pairs. Adenine (A) and guanine (G) always pair up together. Cytosine (C) and thymine (T) always pair up together. In humans, DNA consists of about 3 billion base pairs. Each base pair also connects to a sugar molecule or a phosphate molecule. Together, the base pair, the sugar molecule, and the phosphate molecule are called a nucleotide. The nucleotides form a spiral called a double helix.
Cells can replicate their DNA. This is important because the DNA carries all of the information for making a cell’s proteins. Cells need to reproduce to make new cells. Before a cell can reproduce, it must make a copy of its DNA.
There is a process that happens which, in short, “unzips” the DNA. An interesting enzyme called DNA polymerase “walks” down the DNA strand and adds new nucleotides to the the DNA strand. It looks at the half of a base pair that is in the strand attaches the other half of that base pair.
Each string of DNA has genes inside it. Genes are a set of instructions that tell a cell how to grow or how to make a certain protein. A DNA test focuses on a person’s genes (or specific parts of certain genes) in order to get results.
How does DNA work? In short, it puts together nucleotides that form a double helix. When the DNA needs to replicate, it unzips. A special enzyme takes one part of the unzipped zipper and puts the missing base pairs back together (with brand new pieces). This process is how cells reproduce. Each DNA strand has genes inside it.
Image by Michael Knowles on Flickr
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