In Systemic Tissue Fluids, the Enzyme Carbonic Anhydrase Catalyzes the Reaction

question 60

Multiple Choice

In systemic tissue fluids, the enzyme carbonic anhydrase catalyzes the reaction CO₂ + H₂O  H₂CO₃ (which then can dissociate into H⁺ and HCO₃^-) . In fact, CO₂ released from cells is converted to HCO₃^- ions and travels in that form in the bloodstream. HCO₃^- is reconverted to CO₂ + H₂O in the pulmonary capillaries by the same enzyme, and there the CO₂ is exhaled. How is it possible for the same enzyme to catalyze reverse reactions?

• A)The direction of a reversible reaction is influenced by the concentrations of reactants and products. In pulmonary circulation, the low CO₂ concentration favors the formation of CO₂ and H₂O.
• B)There must be two forms of carbonic anhydrase. One form catalyzes the forward reaction CO₂ + H₂O  H₂CO₃ and the other catalyzes the reverse reaction H₂CO₃  CO₂ + H₂O.
• C)The lungs contain an allosteric inhibitor that prevents the formation of carbonic acid.

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Definitions:

Decay

The gradual reduction in the strength or quantity of something, used metaphorically for the fading of memories over time.

Awake

The state of being conscious, alert, and aware of one's surroundings after sleep.

Proactive Interference

Proactive interference occurs when old information hinders the recall of newly learned information.

Retroactive Interference

A phenomenon in which newer memories interfere with the recall of older memories already stored in the brain.