What Is DNA?
DNA, or deoxyribonucleic acid, is a molecule that contains the genetic instructions for the development, functioning, growth, and reproduction of all known living organisms. It is typically found in the nucleus of eukaryotic cells and consists of two long strands forming a double helix structure. Each strand is made up of a backbone of sugar and phosphate groups linked by nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair specifically—A with T and C with G—encoding the genetic code in sequences known as genes.
Key Functions of DNA
DNA serves as the blueprint for life by storing biological information that is passed from parents to offspring during reproduction. It directs protein synthesis through transcription into messenger RNA (mRNA) and translation into proteins, which perform most cellular functions. DNA also enables replication, allowing cells to divide and organisms to grow. Mutations in DNA sequences can lead to variations, some beneficial and others harmful, influencing evolution and disease susceptibility.
Practical Example: Genetic Testing
In medicine, DNA analysis is used in genetic testing to identify mutations associated with hereditary diseases. For instance, testing for the BRCA1 and BRCA2 gene mutations helps assess a person's risk of developing breast or ovarian cancer. A sample of blood or saliva is sequenced to detect these alterations, enabling early intervention such as increased screening or preventive surgeries, as seen in high-profile cases like Angelina Jolie's decision based on her test results.
Importance and Applications in Medicine
DNA's role in medicine is transformative, underpinning diagnostics like PCR for detecting infections, pharmacogenomics for tailoring drug responses, and therapies such as gene editing with CRISPR-Cas9 to correct genetic disorders like sickle cell anemia. It supports personalized medicine by analyzing individual genomes to predict disease risks and optimize treatments, reducing trial-and-error in healthcare and improving outcomes for conditions from cancer to rare genetic diseases.