How Genes, Environment, and DNA Work Together

All living things have DNA, which is found inside the nucleus of cells. DNA contains instructions for building and running your body. These instructions are organized into sections called genes. Each gene gives directions for making a specific protein, and proteins help control traits such as height, growth, and body functions.

You get your DNA from both of your parents. Half of your DNA comes from your mother and half comes from your father. This means that most traits, like birth weight or eye color, are influenced by genes from both parents, not just one.

However, having a gene does not always mean it is being used. Some genes can be turned “on” or “off.” When a gene is turned on, it is used to make a protein. When it is turned off, the protein is not made. One important way the body controls this is through a process called methylation.

Methylation happens when small chemical groups (called methyl groups) attach to DNA. When a gene is methylated, it is usually turned off, meaning it cannot be used to make its protein. When a gene is not methylated (unmethylated), it is more likely to be turned on and active.

For example, there is a gene called IGF2 that helps control growth before birth. If the IGF2 gene is active, it produces a protein that helps a baby grow larger. If the gene is turned off, less of this growth protein is made.

The environment can also affect how genes work. Things like nutrition, stress, or exposure to chemicals can change methylation patterns. For example, if a mother does not get enough food during pregnancy, it can change how certain genes are turned on or off in the baby.

Even more interesting, some of these changes can be passed down to future generations. This means that environmental effects, like famine, can influence not only the children but sometimes even their children. Scientists call this type of inheritance epigenetics, which means changes in gene activity without changing the DNA sequence itself.

In summary:

• Genes are made of DNA and code for proteins

• You inherit genes from both parents

• Methylation turn genes off

• Unmethylated genes are  turned on / made active

• The environment can affect gene expression

• Some of these changes can be passed to future generations

1. Which statement best describes where genes come from?
(1) Genes come only from the mother
(2) Genes come only from the father
(3) Genes come from both parents
(4) Genes are created after birth

2. What is the main function of a gene?
(1) To store energy for the cell
(2) To build proteins that affect traits
(3) To break down food molecules
(4) To transport oxygen in the blood

3. What usually happens when a gene is methylated?
(1) The gene becomes more active
(2) The gene is turned off
(3) The DNA is destroyed
(4) The gene is copied faster