Relationship Between Calories & Cellular Respiration
The form of energy the body gets from food calories is not the same form of energy it uses to power its activities. The process that converts the chemical energy in food to metabolically usable high-energy phosphate bonds is called cellular respiration.
A Calorie is the unit used to measure the heat energy required to increase the temperature of 1 kilogram of water by 1 degree Celsius.
Production of Carbohydrates
Through a process called photosynthesis, plants absorb and convert the sun’s energy into chemical energy. This chemical energy is held in the molecular bonds that link the carbon, from the plant’s carbon dioxide molecules, to its water molecules, forming carbohydrates. Carbohydrates are the source of calories, the energy in food.
Other Sources of Calories
The two other energy-containing food molecules, fats and proteins, are derivatives of carbohydrates.
Through the process of digestion, the carbohydrates, fats and proteins in foods are broken down into glucose, fats and amino acids, respectively. These nutrients are absorbed into the bloodstream, which transports them to the cells. In the cells they are catabolized (broken down) to synthesize the high-energy phosphate bond ATP (adenosine triphosphate), which drives the body’s metabolic processes.
Types of Cellular Respiration
Each type of energy molecule (carbohydrate, fat and protein) follows a different pathway of catabolism leading to ATP production.