Deoxyribonucleic acid (DNA) is the molecular blueprint for life, encoding instructions that guide the development and function of almost all living organisms. Structurally, DNA is a double-stranded helix formed by four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair specifically (A with T, C with G) to create a complementary sequence. The order of these bases determines the genetic instructions within an organism.

A genome refers to the entire set of an organism's DNA, comprising billions of base pairs in humans. Encoded within the genome are genes, which provide the instructions for synthesizing proteins. These proteins form the building blocks of cellular structures and regulate vital biochemical processes. Mutations or changes in DNA can disrupt normal protein function, leading to conditions such as cancer and genetic disorders.

CRISPR-Cas9 is a precise gene-editing tool that allows scientists to modify DNA sequences. It is widely used to study gene functions, create disease models, and develop potential therapies for genetic disorders.