Is there anything smaller than DNA?

Safiya Zaloum

You might have heard of DNA and that it is really tiny! But is there anything smaller than DNA?

What is DNA?

As humans, our bodies are made up of really small things called cells. You can think of these cells like the bricks used to make a house, all coming together to make us a whole human! We have different types of cells in our body, for example our skin cells are different to our blood cells which are different to our heart cells! This is because specific types of cells work together to perform specific functions.

We can’t see our cells just using our eyes. If you take a look at your arm and find a tiny hair, our cells are even smaller than that! We need a special piece of equipment to be able to see cells called a microscope. This is a bit like a super strong magnifying glass that can zoom in so we can see things that are very tiny! Adult humans are made up of over 30 trillion cells! Check out this cool resource where you can zoom in to see the size of cells compared to small foods such as a grain of salt!

DNA is found inside our cells so we would need to zoom in even further using a microscope to see it. DNA can be thought of like instructions that tell our body how to be our body. Think of it as a big instruction booklet. Different sections are called genes, and each gene tells our body how to do one specific thing. For example, one gene might tell your body what hair colour to make. DNA is found inside every cell and is essentially what makes you, you! You inherit half of your DNA from your mum and half from your dad.

Is there anything smaller than DNA?

DNA is really small but there are things smaller than DNA! Your DNA can be broken down even further into nucleotides. These nucleotides are like blocks of lego used to build your DNA. Each contains a phosphate group, a sugar group and a nitrogen base. There are 4 different types of nitrogen base – A, T, G and C . Think of these like the code that the instructions booklet is written in with these bases making up the language of the code. Scientists have to decipher this code to work out what genes do. This code is slightly different in different people which is why we don’t all look and act in the same way. The sequence of these bases make up genes and the order of the bases means we can have different variations of each gene, leading to people having different eye colours for example.

DNA is made up of the nucleotides which are molecules. A molecule is the smallest possible unit of a substance that can still be identified as that substance. A molecule can contain one or more elements but if we break a molecule, like a nucleotide or one molecule of table salt down further, it won’t be identifiable as either of those things.

Molecules are made up of atoms which are the smallest particles of chemical elements that can exist. If you have seen the periodic table, this shows all of the elements that scientists know of so far. Everything in the universe is made up of elements. For example, salt is made up of the elements sodium and chlorine, and water is made up of hydrogen and oxygen. Humans are more complicated, but we are mostly made of the elements hydrogen, oxygen, carbon and nitrogen. 

Atoms however, are made of smaller parts too! The nucleus or the centre of the atom is made of protons and neutrons and this centre is orbited by electrons. Think of these like the planets orbiting the Sun in our solar system. Electrons cannot be broken down any further but the protons and neutrons at the centre of an atom are made up of 3 quarks each. Quarks are the smallest things that we know of that cannot be broken down into anything smaller!

So there are lots of things smaller than DNA. All life is made up of molecules which are made up of atoms which are made up of even smaller parts!