Common Misconceptions

Misconception: "Genes and DNA are the same thing."

Reality: DNA is the molecule; a gene is a specific section of that molecule. Think of DNA as a very long sentence and a gene as one word within it. The entire sentence (plus many non-coding sections) is DNA; individual words (coding sections) are genes. Humans have about 20,000 genes, but only around 1.5% of human DNA consists of genes — the rest has regulatory and other functions.

Misconception: "Each chromosome contains just one gene."

Reality: Each human chromosome contains thousands of genes. Chromosome 1, the largest, contains around 2,000 genes. Chromosomes are enormous DNA molecules — if stretched out, each chromosome would be several centimetres long.

Misconception: "All cells in your body contain different DNA."

Reality: With the exception of mature red blood cells (which have no nucleus), almost every cell in your body contains identical DNA. What differs between cell types is which genes are switched on or off — muscle cells express muscle-specific genes; nerve cells express nerve-specific genes.

Misconception: "The genome only includes genes."

Reality: The genome includes all the DNA in an organism, including non-coding regions, regulatory sequences, and sections whose function is still being investigated. Only a small fraction of the total genome codes for proteins.