DNA (Deoxyribonucleic acid)
By
Cancer Council NSW
Deoxyribonucleic acid (abbreviated DNA) is the molecule that carries the genetic instructions for the growth, development and functioning of most organisms, including humans.
DNA is made up of smaller subunits called nucleotides, and each nucleotide consists of a sugar, a phosphate group and one of four bases:
- Cytosine [C]
- Guanine [G]
- Adenine [A]
- Thymine [T]
These bases pair up (A with T, C with G) to form a unique genetic code that determines your traits. Long chains of these paired bases twist into a double helix, which looks like a twisted ladder.
Within cells, DNA is organised into genes which are then packaged into chromosomes. DNA is passed from parents to offspring.
Cancer cells can also release pieces of DNA into the bloodstream, called circulating tumour DNA (ctDNA), which can then be detected through a blood test and used as a biomarker.
ctDNA (circulating tumour DNA): Small pieces of DNA released by tumour cells into the bloodstream. ctDNA can sometimes be measured through a blood test and used as a biomarker.
DNA methylation: A process where small chemical groups, called methyl groups, attach to DNA. These methyl groups can affect how active a gene is, often by reducing or switching off gene activity, without changing the DNA sequence itself.