Genetic Terminology 101: Understanding DNA, Genes, SNPs, and More

Glossary

DNA: DNA, short for deoxyribonucleic acid, is like the instruction manual for your body. It contains all the information needed to build and maintain you.  Your DNA sequence is what forms your genetic code, which tells your cells how to make proteins and carry out all their functions. 

Nucleotides: Nucleotides are the building blocks of DNA, like how letters combine to make up a word. There are four different bases: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases always pair up in a specific way: A with T, and C with G. The order of these letters is what gives instructions for making proteins. 

Gene: Genes are specific sections of DNA that carry the instructions for making proteins. Proteins are the workhorse molecules of your body, responsible for a vast range of functions, from building tissues to fighting off infections. Each gene has a unique sequence of bases (nucleotides) that determines the specific protein(s) it codes for.  

Allele: Alleles are different versions of the same gene. Not every person has all possible alleles of a gene. Imagine you have a gene for eye color. There might be different alleles for this gene, such as an allele for brown eyes and an allele for blue eyes. You inherit one allele for each gene from your mother and one from your father. The allele can be the same (both alleles code for brown eyes) or different (one codes for brown eyes and one for blue). The combination of alleles you inherit determines your specific traits. Some alleles are dominant (meaning they have a stronger effect), while others are recessive (meaning their effect is masked by a dominant allele). 

Chromosomes: Chromosomes are organized bundles of DNA found inside the nucleus of your cells. They contain your genes neatly arranged.  Humans have 46 chromosomes that are arranged in 23 pairs. You inherit one chromosome from each pair from your mother and one from your father. 

Genome: Your genome is your complete set of DNA. In humans, this consists of 23 pairs of chromosomes as well as a small bit of DNA contained in a part of the cell called the mitochondria. It includes all your genetic information that allows you to develop, function, and grow. 

SNPs: SNPs, or Single Nucleotide Polymorphisms, are the most common type of genetic variation. They occur when a single nucleotide is changed in a DNA sequence. Think of it as a small typo in a sentence. Most SNPs don't cause any problems, but some can slightly change the shape or function of a protein or affect how a gene is expressed. SNPs can influence various traits, such as hair color or food sensitivities, and can also affect how you respond to medications. 

Epigenetics: Epigenetics refers to changes in how genes are expressed without altering the underlying DNA sequence. It's like adding sticky notes to your instruction manual, telling your cells to read certain parts more or less often. These changes are influenced by environmental factors and lifestyle choices. One of the most common epigenetic mechanisms is DNA methylation, where a chemical group is added to a DNA base, often turning off a gene, meaning the levels of the protein could be reduced or turned off entirely.