By Karen G Blaettler, Updated Aug 30, 2022
Models used in academic or demonstration settings are far more valuable when they are accurately, understandably, and legibly labeled.
DNA is a twisted ladder composed of six distinct components. The backbones are built from alternating deoxyribose sugars and phosphate groups, while the rungs are formed by pairs of nitrogenous bases. Adenine pairs with thymine, and cytosine pairs with guanine. Because of their chemical structures, these bases combine only in these specific pairings. Coloring each base—for example, yellow for adenine and blue for thymine—greatly enhances visual comprehension. (See Resources to practice constructing a DNA model.)
Hydrogen bonds hold the base pairs together but allow them to separate during replication. Depending on your project’s requirements, you may need to display these bonds. If so, they can be represented with toothpicks, small magnets, or even glitter and glitter glue.
Choose a simple, sans‑serif font that is easy to read from a distance. Adjust the font size so that labels remain legible when the model is viewed at the expected distance. Consistency in font choice, size, and format across all labels helps the viewer quickly understand the structure.
Once the model is built, label each part clearly and accurately. A comprehensive label should include the model’s name, the maker’s name, the date of construction, the instructor’s name, and the class title. If the assignment requires an explanatory paragraph, describe the double‑helix structure and discuss DNA’s significance. Some projects also ask for the names of the scientists who discovered the structure—James Watson, Francis Crick, Rosalind Franklin, and Maurice Wilkins.
Label the phosphate molecule: A phosphate group consists of one phosphorus atom bonded to four oxygen atoms. These groups form the rungs that connect the sugar backbones and contribute to the twist of the helix.
Label the deoxyribose molecule: Deoxyribose is a five‑carbon sugar lacking one oxygen atom compared to ribose. It links to the nitrogenous bases and forms the backbone’s sugar component.
Label the base pairs: Each rung of the ladder contains one base pair—adenine (A) with thymine (T) or guanine (G) with cytosine (C). The chemical structures of these bases prevent any other pairings. If the instructions call for relative size, note that adenine and guanine are slightly larger molecules.
Adenine and thymine: Label one adenine as “Adenine (A)” and its paired thymine as “Thymine (T).” Afterward, you may mark additional adenines with “A” and thymines with “T” as long as the initial labels are present.
Guanine and cytosine: Similarly, label one guanine as “Guanine (G)” and its paired cytosine as “Cytosine (C).” Subsequent guanines and cytosines may be marked with “G” and “C” once the full names are shown.
If your model requires hydrogen bonds to be shown, carefully place markers at the bonding sites between adenine and thymine, and between guanine and cytosine. When a marker cannot sit exactly on the bond, position it as close as possible. Use arrows that cross the model minimally to avoid visual clutter.
Identify a nucleotide: A nucleotide is a unit comprising a phosphate group, a deoxyribose sugar, and a nitrogenous base. Labeling a nucleotide should highlight all three components as a single, connected unit. Connect the label to the nucleotide with arrows, strings, or matching stickers.
