Proteins that act as catalysts?

RUHS, Jaipur, PB B.Sc Nursing Entrance-2021

Biochemistry & Nutrition

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2021

Explanation

Enzymes are specialized proteins designed to act as biological catalysts, accelerating metabolic reactions.
They function by providing an alternative reaction pathway with a lower activation energy, thus increasing the rate of reaction.
Each enzyme is highly specific to its substrate, a concept often described by the 'lock and key' or 'induced fit' model.
The vast majority of biological catalysts are proteins, with the exception of a few RNA molecules known as ribozymes.

Option B: Hormones are chemical messengers that travel through the bloodstream to target cells to regulate physiological processes like growth, metabolism, and mood. They do not catalyze chemical reactions.
Option C: Saliva is a complex biological fluid secreted by salivary glands. While it contains enzymes, most notably amylase which begins starch digestion, saliva itself is the medium, not the catalyst.
Option D: Antigens are molecules, typically proteins or polysaccharides on the surface of pathogens or foreign cells, that trigger an immune response. Their role is to be recognized by the immune system, not to catalyze reactions.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Biochemical role of proteins as catalysts as background academic context rather than a clinical decision trigger.
Understanding the function of enzymes is fundamental to clinical diagnostics. Nurses often handle blood samples for enzyme assays and must understand the implications of the results.
Elevated levels of specific enzymes in a patient's blood serum are key biomarkers for diagnosing diseases. For instance, high levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) point towards liver damage.
What if? If a patient presents with chest pain and their blood work shows elevated levels of Creatine Kinase-MB (CK-MB) and Troponin, the nurse should anticipate and prepare for interventions related to an acute myocardial infarction, as these are specific cardiac markers.

How to Approach the Question

This is a factual recall question that tests your knowledge of basic biochemistry definitions.
First, break down the question stem into its key components: 'Proteins' and 'catalysts'.
Systematically evaluate each option based on this definition.
Recall or deduce the primary function of each term. An 'enzyme' is the specific term for a biological catalyst.
Eliminate the other options by identifying their distinct roles: Hormones are messengers, Saliva is a fluid medium, and Antigens are immune system triggers.
Confirm your choice by remembering that the defining characteristic of an enzyme is its catalytic function as a protein.

Concept Tested & Keywords

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E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) pp. 75-77, 73-75

E6 textbook of Applied Biochemistry and Nutrition & DieteticsHarbans Lal (pp 26-464 of 479) p. 126-128