When you are hungry, how do you feel? If you are like most people, you feel sluggish, a little dizzy, and weak. Weakness is your body's way of telling you that your energy supplies are low. Food serves as your source of energy. But how does the food you eat get converted into a usable form of energy for your cells? The answer is cellular respiration.
When you eat, your body digests the food into smaller chemical compounds like sugars (glucose), fats, and proteins. These nutrients enter your cells and are converted into adenosine triphosphate (ATP). ATP is a source of usable energy for cells and is the key energy molecule for all biological organisms.
Directions: Watch the video Energy Consumption: An Overview for a look at the different cellular processes responsible for generating and consuming energy. At this point, try not to worry about the names of compounds or the details of the processes shown. Watch for a general overview. It's actually quite amazing.