Final answer:
Large molecules must be broken down into smaller ones to be absorbed by cells for nutrition and energy. This process, called chemical digestion, involves hydrolysis catalyzed by enzymes. Catabolism of complex molecules releases energy and provides building blocks for cell functions.
Step-by-step explanation:
Importance of Breaking Down Large Molecules
Breaking down large molecules into smaller ones is essential for several reasons. Firstly, large molecules present in food cannot be directly absorbed by the digestive epithelium because they are too large to pass through the cell membrane, and they could potentially damage cellular structures, such as the nuclear membrane. Thus, these molecules must be broken down to prevent cellular damage.
Chemical digestion is the process by which enzymes catalyze the hydrolysis of complex food molecules, like proteins, fats, and carbohydrates, into simpler molecules. For example, proteins are broken into amino acids. These smaller molecules are then easily absorbed by the blood or lymph and transported to the cells, where they can be used as building blocks for new proteins, or as a source of energy.
Moreover, the process of catabolism not only makes nutrient absorption possible but also releases energy that cells need for various functions. Cells require energy for activities ranging from muscle contraction to the synthesis of new molecules. Therefore, the digestion of large molecules into their monomeric forms is a critical step in energy release and the continuous supply of raw materials for the body.