Definition and Primary Role of DNA
Deoxyribonucleic acid (DNA) is the molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses. In biology, DNA's primary role is to store and transmit hereditary information, serving as the foundation for traits passed from parents to offspring.
Structure and Key Functions
DNA consists of two long strands forming a double helix, composed of nucleotides with bases adenine (A), thymine (T), cytosine (C), and guanine (G). It functions through replication to copy genetic information during cell division, transcription to produce messenger RNA (mRNA) for protein synthesis, and as the template for encoding proteins that perform most life functions.
Practical Example: DNA in Trait Inheritance
Consider eye color in humans: Specific genes on DNA determine the production of pigments like melanin. During reproduction, each parent contributes half of the child's DNA, combining alleles to result in traits such as blue or brown eyes, illustrating how DNA governs phenotypic expression.
Importance and Real-World Applications
DNA's role is crucial for understanding evolution, as mutations drive species adaptation, and in medicine, where it enables genetic testing for diseases like cystic fibrosis or therapies such as gene editing with CRISPR. In biotechnology, DNA sequencing supports forensics, agriculture, and personalized medicine.