DNA and RNA: Structure, Types
Start with the big picture
DNA consists of two antiparallel strands arranged in a right-handed double helix, with a negatively charged deoxyribose-phosphate backbone. Complementary base pairing—A with T and G with C—underlies Chargaff’s rule, while base stacking also helps stabilize the helix. DNA can adopt distinct structural forms, become compacted by supercoiling, and occur in mitochondria as circular DNA. RNA is generally single-stranded and contains ribose and uracil; internal base pairing can form hairpins and stem-loops. Its functional classes include mRNA, rRNA, tRNA, and several regulatory or processing RNAs. The ribose 2′-OH makes RNA more susceptible to alkaline hydrolysis, whereas DNA’s exclusion of uracil supports repair of cytosine deamination errors.
What you'll learn
- Describe DNA strand orientation, backbone structure, and complementary base pairing.
- Distinguish DNA structural forms and explain the roles of grooves and supercoiling.
- Identify key features and functions of mitochondrial DNA.
- Compare major RNA classes by structure and function.
- Explain how RNA chemistry and DNA’s use of thymine relate to stability and repair.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
