Which type of protein facilitates all chemical reactions of a cell?

• A. Hormones
• B. Receptors
• C. Antibodies
• D. Enzymes

Answer: (D)

Verified step by step guidance

1. Begin by understanding the role of proteins in biological systems. Proteins are large, complex molecules that play many critical roles in the body, including catalyzing metabolic reactions, DNA replication, responding to stimuli, and transporting molecules.
2. Identify the function of enzymes. Enzymes are a type of protein that act as catalysts in biochemical reactions, meaning they speed up reactions without being consumed in the process. They are essential for facilitating nearly all chemical reactions in a cell.
3. Differentiate enzymes from other types of proteins listed in the problem. Hormones are signaling molecules that regulate physiological processes, receptors are proteins that receive and respond to chemical signals, and antibodies are proteins that recognize and neutralize foreign objects like bacteria and viruses.
4. Recognize that enzymes are unique in their ability to lower the activation energy of reactions, making it easier for the reaction to occur. This is crucial for maintaining the cell's metabolism and overall function.
5. Conclude that enzymes are the correct answer because they are the proteins responsible for facilitating all chemical reactions within a cell, unlike hormones, receptors, or antibodies which have different roles.