Transcription 22/11/2025, 6:47:38 PM

Notes

• Subtopic: Chemical Pathways When you are hungry, how do you feel? If you are like most people, your stomach may seem empty, you might feel a little dizzy, and above all, you feel weak. The sensations produced by hunger vary from one person to the next, but the bottom line is always the same. Our bodies have a need for food, and they have their own ways of telling us when we need it. Food provides living things with the chemical building blocks they need to grow and reproduce. Food serves as a source of raw materials from which the cells of the body can synthesize new molecules. Most of all, food serves as a source of energy. • Subtopic: Chemical Energy and Food How much energy is actually present in food? Quite a lot. One gram of the sugar glucose (C₆H₁₂O₆), when burned in the presence of oxygen, releases 3811 calories of heat energy. A calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius. The Calorie (capital "C" used on food labels) is a kilocalorie, or 1000 calories. Cells, of course, don’t “burn” glucose. Instead, they gradually release the energy from glucose and other food compounds. This process begins with a pathway c...