Which of the following is not a function of carbohydrates?
They are used in structural roles.
They are catalytic components of enzymes.
They play key roles in processes that take place on the surface of cells.
They are major energy sources.
The correct answer and explanation is:
The correct answer is: They are catalytic components of enzymes.
Carbohydrates are not typically catalytic components of enzymes. Enzymes are primarily proteins or RNA molecules that act as catalysts in biochemical reactions. While carbohydrates play essential roles in various biological functions, their involvement in catalysis is not as a direct participant in enzyme reactions.
Explanation:
Carbohydrates serve a variety of functions in living organisms, including:
- Structural Roles: Carbohydrates are crucial for the structural integrity of cells and tissues. For example, cellulose, a polysaccharide made up of glucose units, provides structural support in plant cell walls. Similarly, chitin, another polysaccharide, is found in the exoskeletons of arthropods and insects.
- Surface Processes: Carbohydrates are involved in processes that occur on the surface of cells. Glycoproteins and glycolipids, which are carbohydrates bound to proteins or lipids, play important roles in cell recognition, signaling, and communication. These molecules are often found on the cell membrane and are involved in interactions with other cells, immune responses, and pathogen recognition.
- Energy Source: Carbohydrates are a major source of energy for the body. Simple sugars like glucose are quickly metabolized to release energy, while more complex carbohydrates like starch are stored for later use. In humans and other animals, carbohydrates are broken down in the digestive system to provide energy for cellular activities.
- Not Catalytic Components of Enzymes: While carbohydrates play a role in the structure of some enzymes, they do not function as catalysts. Catalysis is generally carried out by proteins (enzymes) or RNA molecules (ribozymes), which speed up chemical reactions without being consumed in the process. Carbohydrates, in contrast, do not have this catalytic ability.
Thus, carbohydrates do not serve as catalytic components of enzymes, which is why this statement is incorrect.