Chromatin Pipecleaner Models

Public summary: 

Humans have 19,000 genes. How are only certain genes turned on in each cell so that brain cells express brain genes, but not heart genes and vice versa? Here we make fun chromatin models to explore epigenetics.

Explore the world of epigenetics, using pipecleaners and corks to model DNA and the chemical changes done to it to turn genes on and off.
Useful information
Kit List: 

Pipecleaners (much better if they are made of two different colours)
Plastic beads (prefereably all of the same shape and colour on the day but no specific colour or shape is needed)
Paper bowls to put the separate components in
Small circular stickers

Packing Away: 

The kids are very welcome to take home their chromatin models but preferably keep one or two good examples as models to help the next demonstrators. Put stickers back in pack and beads in the bag provided. Corks and bowls can be kept loose.


Humans have 19,000 genes. How are only certain genes turned on in each cell so that brain cells express brain genes, but not heart genes and vice versa? Genetic information (i.e. what makes you, you) is stored in DNA. All cells in the human body contain all of the DNA needed to make any cell in the body, but we don't want heart cells expressing genes that are meant to be specific to the liver and vice versa. How can we make sure that some genes are turned on and some genes are turned off? Here we need to look at the fascinating world of epigenetics - it's not what genes you have, but how you use them that matters!

(Put some corks and some beads in separate paper bowls for the kids to draw from when making their models).

DNA is a long complex molecule that contains all of the genes of the cell. It is formed of a double helix (show the pipe cleaner), which means that you have two strands wrapped around each other. It is very long and thin reaching 2m in every single cell in the human body. (Here you can show the kids how big 2m is relative to your height). If you stacked all the DNA from every cell in the human body it would be twice the diameter of the solar system! How on Earth can all of this DNA fit inside a cell, which is the is 25 times smaller than a grain of sand?

Histone proteins are essential for wrapping up the long, thin DNA, so it doesn't get all tangled and still fits into a nice, small cell. [For older children, you can explain how there are 5 main types of histones and how they come together to form a repeating unit called a nucleosome]. (Wrap the pipecleaner around a cork, twisting it at the end to hold it secure).

To read genes within the DNA, other proteins must be able to bind to the DNA. If something prevents this, the gene cannot be read and so is not expressed. Epigenetic marks can either make it easier or harder for the DNA to be read.

Methylation marks make it harder for DNA to be read by getting in the way of the gene reading machinery. (Show the kids the red beads and slide one on to the free end of the pipecleaner to show a gene which is not being read. You can add as many or as few as you like. You can then add the second histone on to the DNA in the same way that you did the first one).

Histone modifications can make it easier or harder for the gene reading machinery to reach the DNA that is wrapped around the histones. Some of these chemical modifications enhance the ability of histones to bind to DNA (i.e. increasing positive charge on histones such that they bind more readily to negatively charged phosphate groups in the DNA backbone), so it is harder for the genes to be read, whereas some loosen the histones' grasp on the DNA (i.e. neutralizing the positive charge on histones such that they are less keen to interact with negatively charged DNA). (Here you can add the circular stickers onto the corks. The final product should have two histones, a few methylation beads and several different coloured stickers).

[For older children, you can discuss how environmental changes which affect the mother can impact the epigenetics of the baby and so how the genes will be read during the child's life. For example, the children of overweight mothers are much more likely to become overweight themselves than the children of mothers of a healthy weight. However, if an overweight mother does regular, light exercise during the pregnancy, this risk is reduced considerably].

To renew stocks, get stripey pipecleaners and beads (9mm pony beads, roughly £6 for 1000, any colour works)

Risk Assessment
Date risk assesment last checked: 
Sat, 25/01/2020
Risk assesment checked by: 
Matt Worssam
Date risk assesment double checked: 
Sat, 25/01/2020
Risk assesment double-checked by: 
Beatrix Huissoon
Risk Assessment: 

Making a model of chromatin from pipe cleaners, corks and beads

Hazard Risk Likelihood Severity Overall Mitigation Likelihood Severity Overall
Pipe cleaners Sharp ended pipe cleaners may scratch. 4 2 8 Fold over the tips and warn children about scratches.
Call a first aider in the event of severe scratches.
2 2 4
Pipe cleaners Eyes may be poked if children are silly with the pipe cleaners. 3 3 9 Encourage children to be sensible with pipe cleaners, ask them to leave if they are being silly.
Call a first aider if an accident occurs.
1 3 3
Beads Choking risk if the children swallow the small beads. 2 4 8 Do not let children under 3 make the models. Children below ~age 8 should be supervised by parents. CHaOS volunteers should also oversee carefully and prevent any beads going in mouths. In case of injury call first aider. 1 4 4
Corks Children may trip over corks if they have fallen on the floor. 2 2 4 Pick up corks immediately if they fall on the floor, or ask the children to.
Call a first aider in the event of an accident.
1 2 2
Experiment photos: