While studying for A-Level biology, I initially struggled to distinguish between the various polysaccharides. Glycogen, starch, amylose, and amylopectin are quite complicated yet fascinating molecules, so I built models to help me understand their structures and roles.

I have made two models: one of amylose, and one of amylopectin/glycogen. Both of these models are made of 3D-printed hexagonal beads strung together with pipe cleaners, aka chenille stems, of different colors. The hexagonal beads represent the sugar glucose and the pipe cleaners of different colors represent different types of chemical bonds joining the sugar molecules.

The amylose model is a long, coiled pipe cleaner strung with beads. Adjacent parts of the coil are joined by short pipe cleaners of a different color.

The amylopectin/glycogen model is a single long pipe cleaner strung with beads, with other shorter pipe cleaners joining to the long pipe cleaner - the 'backbone' - and creating a branched structure.

You will need:

1. A resin or filament 3D printer
2. Resin or filament to supply the printer
3. Pipe cleaners/chenille stems of at least 2 different colors, with a minimum quantity of 4 each
4. 3D model files given below. Multiple formats are given to increase compatability for different slicer programs.

Start printing the hexagonal beads. Print 30-50, with spares.

Print settings:

1. 0.28 mm layer height
2. 2 walls
3. 10% infill, Lightning or Cubic
4. Support OFF

In this section we will create the base for both the amylose and glycogen/amylopectin models.

Start by threading around 10 beads onto a 20-30cm long pipe cleaner. Leave a gap of 1-2 cm between beads. The exact number and spacing isn't important; the pipe cleaner merely needs to be long enough, and the beads must be separated enough, to either form a good coil (in the case of the amylose model) or allow side branches to attach (in the case of the amylopectin/glycogen model).

Additionally, you can twist the end of the pipe cleaner/chenille stem around the end bead to hold the rest of the beads in place and stop them from slipping off, though this is optional.

Instructions for making the 1st model, the amylose model

Take the pipe cleaner strung with beads from Step 2 and gently wind it into a coil. The pipe cleaner can be wound around a cardboard tube or anything else cylindrical to form a more distinct shape. Note: technically, amylose has a left-handed helix structure, so the direction in which you wind the coil matters. (Details given below.) You don't have to do this for a simple model, however.

Optional step:

Adjacent glucose units in an amylose molecule form hydrogen bonds with each other, stabilising the helix structure. To represent this in the model, take a pipe cleaner of a different color (light green in this case) and cut it into small, 5-cm long pieces. Use these pieces to connect adjacent loops of the coil by wrapping them around the the coil (see gif for clarification).

Instructions for making the 2nd model, the amylopectin/glycogen model

Thread 3-5 beads onto smaller, 5-8cm long pipe cleaners to make multiple (3-6) short 'branches'. Cut pipe cleaners of a different color (blue in this case) into 3cm long sections and use them to join the 'branches' to the pipe cleaner strung with beads from Step 2 (the 'backbone'). The new color represents 1,6-glycosidic bonds that give amylopectin and glycogen their characteristic branching structure, similar to a that of a tree.

Here is a short section on the structure, purpose and properties of these molecules. It is written for two types of readers: beginners/general readers, and A-level biology students. As such it has been written with both simple explanations and extra details to accomadate a wider audience.

What are polysaccharides?

Put simply, all of these are big sugar molecules made by linking smaller sugar units together, like beads on a string. For those who want more detail, they are polysaccharides: large macromolecules made of repeating alpha‑glucose monomers joined by glycosidic bonds. Alpha-glucose is an isomer of glucose where the hydroxyl group (-OH) on carbon 1 is positioned below the ring plane, unlike beta-glucose where it is above.

What is their purpose?

The reason cells build sugars into these large molecules is storage. In simple terms, they’re a safe way to keep sugar without it dissolving in water, reacting with molecules and hurting the cell, or upsetting the balance of water flow between the inside and outside of the cell. For a more advanced view, their insolubility prevents disruption of osmotic balance, their compact structure makes them efficient to store, and because they are non‑reducing, they avoid unwanted redox reactions that smaller sugars might trigger.

What Are Their Differences?

Although they share this storage role, the polysaccharides differ in structure. In everyday language: animals use glycogen, while plants use starch, which itself is a mix of amylose and amylopectin. Amylose has only single links, so it is a straight chain that coils into a helix, while glycogen and amylopectin have extra side links that make them branched. For the A‑Level explanation: amylose contains only 1,4-glycosidic bonds, producing a helical chain. Amylopectin and glycogen, by contrast, contain both 1,4- and 1,6-glycosidic bonds, giving them branched structures. Glycogen is even more highly branched than amylopectin, which makes it especially efficient for animals.

The branching matters because it changes how quickly the stored sugar can be released. In simple terms, branched molecules can be broken down faster, so the cell gets energy more quickly. In more detail, the branched architecture increases the number of terminal glucose units, which enzymes such as glycogen phosphorylase can attack simultaneously. This allows rapid hydrolysis, feeding glucose into aerobic respiration and ultimately producing ATP.

Note: Amylose typically forms a left-handed α-helical structure, so it twists clockwise if you look at the coil head-on. Imagine a staircase. If you are descending the stairs and turning to your left, it's a left-handed helix. If you are descending and turning to your right, it is a right-handed helix.

Attribution:

Untitled image. "Carbohydrates" under "Lesson 4: Properties, structure, and function of biological macromolecules". Khan Academy. Accessed 3 November 2025. https://www.khanacademy.org/science/ap-biology/chemistry-of-life/properties-structure-and-function-of-biological-macromolecules/a/carbohydrates

Untitled image. "Carbohydrates" under "Lesson 4: Properties, structure, and function of biological macromolecules". Khan Academy. Accessed 3 November 2025. https://www.khanacademy.org/science/ap-biology/chemistry-of-life/properties-structure-and-function-of-biological-macromolecules/a/carbohydrates