All living things are made up of basic units called cells, which are so tiny that you can only see them through the lens of a strong microscope. Most of the billions of cells in the human body have one nucleus that acts as a control center, housing our 46 chromosomes. A chromosome is a thread-like structure found in the cell’s nucleus, which can carry hundreds, sometimes thousands, of genes.
In humans, a set of 23 chromosomes is inherited from each parent. The genetic material on these 23 chromosomes is collectively referred to as the human genome. Through research, scientists now believe the human genome is made up of about 30,000 genes. Genes direct almost every aspect of the construction, operation, and repair of all living things. For example, genes contain information that determines eye and hair color and other traits inherited from our parents. In addition, genes ensure that we have two hands and can use them to do things, like play the piano.
Genes alone are not all-powerful. Most genes can do little until spurred on by other substances. Although they are necessary in their own right, genes basically wait inside the cell’s nucleus for other molecules to come along and read their messages. These messages provide the cell with instructions for building a specific protein.
Proteins are an important building block in all cells. Bones and teeth, muscles and blood, for example, are formed from different proteins. They help our bodies grow, work properly, and stay healthy. Amino acids are the building blocks of proteins. A gene provides the code, or blueprint, for the type and order of amino acids needed to build a specific protein. Sometimes a genetic mutation (or defect) can occur, leading to the production of a faulty protein. In addition to gene mutations, the environment (the food we eat, the air we breath, or chemicals we are exposed to) can affect the production of a protein by interrupting the translation of the genetic message. Faulty proteins can cause cell malfunction, disease, and death.
Scientists are studying genes to learn more about the proteins they make and what these proteins actually do in the body. They also hope to discover what illnesses are caused when genes don’t work right.