DNA and nucleotides
DNA and nucleotides

DNA is a polymer made from two long strands twisted into a double helix. It can be pictured as a twisted ladder, with the strands forming the sides and paired bases forming the rungs.
Step-by-step lessons on AQA GCSE Biology 6.1.5 DNA structure. Each one builds up to exam-style questions. Start with the foundational topics and build up to the higher-tier material.