Problem 101 - Objective Biology for NEET

Question

\(\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \Leftarrow \mathrm{H}_{2} \mathrm{CO}_{3}\) Carbonic acid Which one of the following statement is incorrect about the above reaction? (a) In the absence of enzyme, the rate of \(\mathrm{H}_{2} \mathrm{CO}_{3}\) formation is about 200 molecules per hour. (b) When carbonic anhydrase catalyses the same reaction, there is no change in the rate of \(\mathrm{H}_{2} \mathrm{CO}_{3}\) formation. (c) The reaction catalyzed by the enzyme shows dramatically higher decrease speed about 600,000 molecules being formed every second (rate becomes 10 million times more). (d) The enzymes carbonic anhydrase occurs in abundance of RBC's.

Step-by-Step Solution

Answer

The incorrect statement is option (b). It falsely claims that the rate of the reaction wouldn't change when catalyzed by the enzyme carbonic anhydrase, which contradicts the known function of enzymes to speed up reactions.

Step 1: Assessment of baseline reaction

The reaction \(\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{H}_{2}\mathrm{CO}_{3}\) happens naturally, producing about 200 molecules per hour according to option (a). This low rate is expected considering the lack of catalysts.

Step 2: Assess claim about enzyme-catalyzed reaction not changing the rate

Option (b) makes an assertion that the rate of formation of \(\mathrm{H}_{2} \mathrm{CO}_{3}\) does not change when catalyzed by the enzyme carbonic anhydrase. This statement is generally implausible as enzymes are known to accelerate the catalytic reactions they're present in.

Step 3: Analyze claim about increased reaction speed with enzyme

Option (c) claims a dramatically increased speed in the enzymatic reaction, to about 600,000 molecules per second. This is a credible claim as enzymes are known to significantly increase the rate of the reactions they catalyze.

Step 4: Verify the natural occurrence of enzyme

Option (d) asserts that carbonic anhydrase is abundantly present in RBC's. This is well-established and thus is correct.

Key Concepts

Carbonic Anhydrase: The Enzymatic Marvel

Carbonic anhydrase is a powerful enzyme that plays a crucial role in facilitating specific biochemical reactions in our body. Its primary function is to accelerate the conversion of carbon dioxide and water into carbonic acid, bicarbonate, and protons, and vice versa. This process is essential for maintaining acid-base balance and enabling efficient gas exchange in the body.
This enzyme is particularly proficient due to its ability to increase reaction rates by a staggering factor—often millions of times faster than without the enzyme. Without carbonic anhydrase, the formation of carbonic acid from carbon dioxide and water is extremely slow, limiting physiological functions like respiration and circulation.

• The enzyme speeds up reactions that are vital for the handling of carbon dioxide in the body.
• It helps cells manage pH levels and supports respiratory processes.

This enzymatic efficiency highlights the need to understand how essential enzymes are to life, especially in multicellular organisms like humans.

Understanding Reaction Rates

Reaction rates tell us how quickly or slowly a reaction takes place. It is a vital concept in chemistry as it helps us gauge the speed at which reactants convert into products. The rate of reaction can be influenced by several factors including temperature, concentration, surface area, and the presence of catalysts such as enzymes.
When considering enzyme catalysis, the reaction rate is significantly affected. For instance, with carbonic anhydrase, the transformation of carbon dioxide and water into carbonic acid occurs at an accelerated pace. Without the enzyme, this process happens at a measly 200 molecules per hour. Introducing carbonic anhydrase into this reaction dramatically speeds it up to approximately 600,000 molecules per second.

• Enzymes lower the activation energy—meaning the energy required to initiate a reaction.
• This results in reactions that not only happen faster but are also more efficient.

Understanding and manipulating reaction rates is fundamental in both biological systems and industrial applications where control over reaction speed is critical.

Role of Red Blood Cells (RBCs)

Red blood cells (RBCs) are essential components of the circulatory system, primarily known for transporting oxygen from the lungs to the body's tissues and carbon dioxide from the tissues back to the lungs. They owe their efficient functioning partly due to the enzyme carbonic anhydrase, which is present in significant amounts within these cells.
RBCs make use of carbonic anhydrase to rapidly convert the carbon dioxide produced by cells into bicarbonate ions, which are more easily transported in the blood. This conversion process helps maintain the acid-base balance in the bloodstream and facilitates the removal of carbon dioxide from tissues.

• RBCs provide a site for efficient gas exchange and transportation.
• They help manage blood pH through interactions involving carbonic anhydrase.
• The abundance of the enzyme within RBCs underscores its importance in respiratory physiology.

The intricate function of RBCs in gas transport and pH regulation can be seen as a fine example of how cellular structures and enzymes work together flawlessly to sustain life.