DNA contains the genetic blueprint for organisms and carries this information from parents to offspring. It has a double helix structure with a backbone of sugars and phosphates, and nucleotides that form base pairs between strands. DNA replicates its structure by separating the strands and using enzymes to add complementary nucleotides to each, generating two new DNA molecules. RNA also contains nucleotides that form base pairs and carries genetic instructions but is single-stranded. There are different types of RNA including mRNA and tRNA that play important roles in protein synthesis.