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Enzymes as Catalysts in Metabolic Reactions Biology Certification Fact
Enzymes speed up metabolic reactions as catalysts without consumption, lowering activation energy via active sites—not glucose, lipids, or hemoglobin—crucial for pathways like glycolysis in General Biology exam prep.
Question
Metabolic reactions require the assistance of ___________ that speed up chemical reactions without being consumed by the reaction.
A. glucose
B. lipids
C. hemoglobin
D. enzymes
Answer
D. enzymes
Explanation
Enzymes function as biological catalysts, primarily proteins that lower the activation energy required for metabolic reactions by stabilizing the transition state through active site binding, precise orientation of substrates, and mechanisms like acid-base catalysis or covalent intermediacy, thereby accelerating reaction rates by factors of millions without undergoing net chemical change or consumption. These globular proteins exhibit specificity for substrates via lock-and-key or induced-fit models, operate optimally at physiological pH and temperature (with denaturation above ~40-50°C), and are regulated by allosteric effectors, inhibitors, or covalent modifications like phosphorylation to fine-tune metabolic pathways such as glycolysis, Krebs cycle, or DNA replication. Unlike glucose (energy substrate), lipids (energy storage), or hemoglobin (oxygen transport), enzymes uniquely facilitate the thousands of interdependent reactions sustaining cellular homeostasis, growth, and response in all living organisms.