Genes
Instructions that help cells do their job.
Genes are present in almost all cells of the body. They contain instructions for making every single part of you. Genes tell the cell what to make and when. We inherit our genes from our parents. This is how certain traits (such as eye colour) are passed through families. Cystic fibrosis happens because of changes in a gene called CFTR.
Read our article explaining how mutations in the CFTR gene can cause cystic fibrosis.