Kaplan Nursing Entrance Practice Exam

What are enzymes in human cells primarily made of?

1. Carbohydrates

2. Nucleic acids

3. Proteins

4. Lipids

The correct answer is: Proteins

Enzymes in human cells are primarily made of proteins. This is because enzymes are biological catalysts that speed up chemical reactions in the body and are fundamentally composed of long chains of amino acids that fold into specific three-dimensional shapes. The unique structure of proteins allows them to interact with substrates and facilitate reactions efficiently. While carbohydrates, nucleic acids, and lipids play essential roles in cellular functions, they do not serve the primary role as enzymes. Carbohydrates are primarily involved in energy storage and providing structural support, nucleic acids are vital for genetic information storage and transfer, and lipids are key components of cell membranes and serve as energy stores. However, the specialized function of catalyzing biochemical reactions is carried out specifically by enzymes, which are indeed proteins.