Scientists Say: Protein

These essential molecules made of amino acids play key roles in cells and bodies

The protein insulin helps the body control the amount of sugar in the blood. Some people have a disease called diabetes. That means their bodies don’t make enough insulin or don’t use it properly.

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Protein (noun, “PRO-TEAN”)

This word describes a type of molecule made up of building blocks called amino acids. Proteins are large molecules that perform many roles in living things. Some proteins are enzymes. These molecules speed up reactions important for life. Other proteins form structures in cells, such as channels that let molecules travel across the cell’s membrane. Proteins can also hold a group of cells together to form a tissue. Some proteins aid the immune system. Antibodies are one such protein. Antibodies allow the body to recognize and respond to invaders such as viruses or bacteria. And some proteins help in the process of making new molecules, including other proteins.    

Structures inside of cells, called ribosomes, build proteins. To make proteins, ribosomes follow instructions in an organism’s DNA. First, a type of molecule called RNA copies these instructions from the DNA. Then, the RNA brings these instructions to the ribosome, which “reads” them. These instructions direct the ribosome to string together amino acids to make a protein.

There are only about 20 amino acids. But different combinations of these building blocks produce a huge number of proteins. Scientists have identified tens of thousands of proteins in the human body. But people may contain hundreds of thousands of proteins.

People need to eat protein as part of a healthy diet. Foods that contain high amounts of protein include eggs, meat, nuts and some veggies. When we eat, our bodies break down the proteins in our food into smaller molecules. Then our cells can then use those molecules to build new proteins.

In a sentence

Insects pack a nutritional punch, in part because they’re full of protein.

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Carolyn Wilke is a former staff writer at Science News for Students. She has a Ph.D. in environmental engineering. Carolyn enjoys writing about chemistry, microbes and the environment. She also loves playing with her cat.

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