DNA, RNA & Protein Synthesis
DNA stores the genetic code in base pairs (A-T, G-C); transcription copies a gene into mRNA (A-U, G-C) in the nucleus, and translation reads mRNA three bases (one codon) at a time at the ribosome to build a protein.
DNA is double-stranded with a deoxyribose sugar; RNA is single-stranded with ribose. Each codon specifies one amino acid, tRNA delivers the matching amino acid, and a mutation that changes a codon can change the protein — the molecular root of genetic disease.