Question

Phenylketonuria (PKU), an inherited disorder, arises when the body cannot properly metabolize the amino acid phenylalanine due to deficiency in the enzyme phenylalanine hydroxylase. This results in a buildup of phenylalanine within the body. Under normal circumstances, this enzyme converts phenylalanine to tyrosine. Which of the following accurately describes the role of enzymes?

1) Enzymes are proteins that act as catalysts in biochemical reactions.
2) Enzymes increase the rate of chemical reactions by lowering the activation energy.
3) Enzymes are specific in their action and can only catalyze a particular reaction.
4) Enzymes are not affected by the reaction they catalyze.

Answer 1

Enzymes are vital biological catalysts specific to particular biochemical reactions, (option 1) and deficiencies in these enzymes can lead to disorders such as phenylketonuria (PKU), where phenylalanine cannot be metabolized into tyrosine effectively.

Step-by-step explanation:

Role of Enzymes in Metabolic Disorders

Enzymes are biological catalysts made predominantly of proteins, fundamental to numerous metabolic processes in living organisms. In the context of phenylketonuria (PKU), a genetic disorder affecting about 1 in every 15,000 births, the enzyme phenylalanine hydroxylase is essential for metabolizing the amino acid phenylalanine into tyrosine. Due to mutations that affect the enzyme's shape or activity, individuals with PKU cannot adequately process phenylalanine, leading to its accumulation and toxic levels in the body, causing damage to the central nervous system and brain. This highlights the enzyme's role as a highly specific catalyst that facilitates biochemical reactions by lowering the activation energy, dramatically increasing the reaction rate without being consumed in the process.

Each enzyme has a unique and specific action, whereby it only catalyzes particular reactions, as is the case with phenylalanine hydroxylase acting on phenylalanine. To manage PKU, patients must adhere to a strict diet low in phenylalanine, avoiding products such as aspartame, which is high in this amino acid. The consequences of enzyme deficiencies, such as in PKU, underline the importance of enzymes in health and disease.