Compare and contrast the metabolism of glucose with the metabolism of complex carbohydrates, proteins & fats. explain where each molecule (or component of the molecule) enters the aerobic cellular respiration pathway, and order each in terms of the amount of energy they produce for the cell.

The energy one can receive from carbohydrate, protein, and fat is determined in calories per gram. 4 calories per gram of energy is provided by carbohydrate or protein, on the other hand, 9 calories per gram of energy is provided by fat.

Fats possesses the maximum amount of energy and proteins have a similar amount of energy as carbohydrates. The human body is developed to utilize carbohydrates as its main source of energy as carbohydrates are burned instantaneously.  Excess energy gained from fat is accumulated in the body for further application.  

Carbohydrates are more easily digested in comparison to lipids and discharge their energy more swiftly. Monosaccharides and disaccharides are water soluble and easier to meditate to and from storage sites in comparison to lipids. Excess storage of fat can result in obesity and other health complications.

Carbohydrates are stored in the form of glycogen in animals while lipids are accumulated as fats. Complex carbohydrates are complex, and long chains of sugar; consume longer to dissociate; provide a source of energy for a prolonged time.

Proteins are large organic compounds formed of amino acids organized in a linear chain. Eight of the amino acids contained in proteins are essential in the human body to subsist. The body requires protein to sustain and substitute tissues and to function and develop.

Protein is not usually used for energy. However, if the body is not getting enough calories from other nutrients or from the fat storage in the body, then protein is used for energy. As proteins are composite molecules, the body takes more time to dissociate them. As a consequence, they are a much slower and enduring source of energy in comparison to carbohydrates.