Our DNA holds the instructions to many important processes within our body. Some people with MND may have changes in their DNA which contribute to the development of the disease, alongside other factors. It is important to understand the critical role that DNA plays within our cells to gain insights into what happens when it changes in MND.
What is DNA and where is it found?
Our DNA is what makes us who we are. DNA is inside every cell in our bodies and is responsible for our appearance like our hair colour, eye colour and height. Our DNA comes from our biological parents and so everyone’s DNA is slightly different from each other, except from identical twins who have the same DNA. This is why we can look like our parents and siblings but not exactly the same.
DNA stands for Deoxyribose Nucleic Acid and this tells us what it is made of. Deoxyribose is the name of the sugar that makes up the outside pieces of the DNA, called the sugar phosphate backbone. Nucleic acid refers to the pieces in between the backbones which hold the information that makes us who we are. DNA is a bit like a twisted ladder; the sugar phosphate backbones are the outside edges and the nucleic acids are like the rungs in between. There are four different nucleic acids which are used to make DNA; Adenosine, Cytosine, Thymine and Guanine. These four are like jigsaw pieces and only fit together in a certain way. Guanine and Cytosine fit together and Adenosine and Thymine fit together so they always pair up in this way.
DNA is the building block for every cell inside our bodies. It provides the instructions to make, maintain and repair cells, as well as making sure they have everything they need to work as they should. Each cell has a nucleus, or control centre, which is where the DNA is found. The DNA in each cell would be 2m long if you stretched it out, so how does it fit into the nucleus of a small cell? It is wound around special structures called histone proteins again and again. These histone proteins are like a bobbin and the DNA is like the thread that wraps around it.
What are genes and what do they do?
Genes are small segments of DNA which contain the instructions to make a particular substance, such as a protein, that our cells need. Our DNA contains around 20,000 genes and we have two copies of each gene in our cells; we inherit one copy from each biological parent. These copies, called alleles, are not always identical and can have slight differences between them.
You can think of genes like recipes, one recipe has the instructions to make one thing and one gene has the instructions to make one product too.
The information in genes is read by the cell and used to make the substances that they need to function properly. Just like we read and follow recipes to make a cake, our cells have machinery that reads, processes, and follows the instructions to make proteins.
What is a protein and why are they important?
Proteins are large structures that are made in our bodies using the instructions in our genes. They are made up of smaller building blocks called amino acids. These building blocks are a bit like beads on a necklace. Our genes tell our cells which amino acids to use, and the order they need to be in, to make a certain protein.
Proteins are usually made of more than one string of amino acids. These strings of amino acids join together and get folded up to make the structure of the final protein. Proteins have different structures depending on the job they carry out in the cells but they are all 3D.
Proteins are essential to our cells working as they should. They carry out many important jobs throughout our cells. There are lots of different types of proteins and each has its own unique function.
Proteins help to:
- transport materials
- create energy and other substances for our cells to use
- receive and process chemical messages
- clean up rubbish inside the cells
- keep the structure of our cells
Our cells need proteins to carry out the work that happens inside, much like workers inside a factory. Without these proteins, our cells wouldn’t work properly and would start to break down. One example of an essential protein is haemoglobin which carries oxygen around our body through the bloodstream. Without this, the cells and organs in our bodies wouldn’t get the oxygen they need to function and keep us alive.
Proteins can play a role in diseases if they don’t perform their jobs properly. For example, some proteins aren’t made correctly or don’t fold in the right way and this means that they can’t carry out their jobs.
How is this linked to MND?
In MND, some genes may undergo changes which mean that the instructions can’t be followed properly anymore. These changes can increase the risk of developing the disease. Sometimes these changes can be passed down through families and this is called inherited MND.
Problems with the instructions can mean that some proteins aren’t made properly and can’t work as they should. These non-functional proteins may become toxic and form clumps in the cell.
You can find out more about how proteins are made from our genes and what happens to them in MND in the next blog.
