The human body is a complex piece of machinery that is kept running by countless smaller moving parts. At the center of all those moving parts are molecules, the smallest group of atoms that perform a function. A video uploaded by SciShow highlights the five most important molecules in the human body, or macromolecules.

“Your body has all sorts of complicated processes going on, and a lot of them are carried out by incredibly powerful molecules,” the video description reads. “We’re not talking nutrients — we’re talking about five of the molecules that keep you ticking!”

1. Deoxyribonucleic acid, or DNA, is not only the largest molecule in our body, but it is also utilized every time our body produces a new cell, which it does two trillion times a day.

2. Pepsin is an enzyme responsible for digesting proteins in food and breaking them down into amino acids.

3. Hemoglobin, a protein found in red blood cells, is tasked with the life or death responsibility of carrying oxygen from the lungs to the body’s tissues and returning carbon dioxide from the tissues back to the lungs.

4. Adenosine triphosphate, or ATP, is not technically considered a macromolecule because of its smaller size, but it still has an important role to play in the human body. In fact, when it comes to the release of energy within the body, there’s no molecule more important than ATP.

5. Cholesterol is often tied to an increased risk for cardiovascular issues, such a heart attack or stroke. However, it is also responsible for producing hormones, chemical messengers that regulate processes that don’t need to happen all the time.