Easy-to-assemble system for constructing DNA and RNA models and simulating replication and transcription. Build a DNA molecule and twist it into a double helix with 10 base pairs per helical turn-the same number as real DNA. Then “unzip” the model to mimic what happens during replication and transcription. Deoxyribose sugars, phosphate groups, nucleotides, and hydrogen bonds are all color-coded. Store the 521 pieces in the sturdy, stackable storage tray with snap-on lid. This kit is a valuable teaching aid to help students visualize not only the structure but also the function of DNA. Includes comprehensive Teacher's Guide. Enough for two models at a time.