Problem 93 - Objective Biology for NEET

Question

The enzyme essential for transport of \(\mathrm{CO}_{2}\) as bicarbonate in blood is (a) Carboxypeptidase (b) Succinic dehydrogenase (c) Carbonic anhydrase (d) Thrombokinase (e) Lactase

Step-by-Step Solution

Answer

The enzyme essential for transport of Carbon Dioxide as bicarbonate in blood is Carbonic Anhydrase (c).

Step 1: Identify the biological concept

Determine which biology area this addresses.

Step 2: Recall relevant principles

Review key concepts.

Step 3: Apply knowledge

Use biological reasoning.

Step 4: State the answer

The answer is: The enzyme essential for transport of Carbon Dioxide as bicarbonate in blood is Carbonic Anhydrase (c).

Key Concepts

CO2 transport in blood

Carbon dioxide (CO₂) transport in the blood is a fascinating and essential physiological process. It ensures that CO₂, a waste product of cellular metabolism, is efficiently removed from the body's tissues and expelled through the lungs. The entire process involves several steps and is crucial for maintaining the body's acid-base balance.

CO₂ can be transported in the blood in three main ways:

• Approximately 7-10% of CO₂ is transported dissolved directly in the plasma.
• About 20% of CO₂ binds to hemoglobin in red blood cells to form carbaminohemoglobin.
• The majority, approximately 70-75%, is transported in the form of bicarbonate (HCO₃⁻). This conversion is facilitated by the enzyme carbonic anhydrase.

Understanding these different transport mechanisms helps us appreciate how the body adapts to varying physiological demands and ensures efficient gas exchange.

Bicarbonate formation

The formation of bicarbonate (HCO₃⁻) is a key element in the transport of CO₂ in the blood. This process begins when carbon dioxide diffuses into red blood cells, where it encounters the enzyme carbonic anhydrase. This enzyme plays a crucial role by catalyzing the reaction between CO₂ and water (H₂O), resulting in the formation of carbonic acid (H₂CO₃): \[ \mathrm{CO}_{2} + \mathrm{H}_{2}\mathrm{O} \rightleftharpoons \mathrm{H}_{2}\mathrm{CO}_{3} \] This carbonic acid is unstable and quickly dissociates into bicarbonate ions (HCO₃⁻) and hydrogen ions (H⁺):\[ \mathrm{H}_{2}\mathrm{CO}_{3} \rightleftharpoons \mathrm{H}^{+} + \mathrm{HCO}_{3}^{-} \] These bicarbonate ions are then transported out of the red blood cells into the plasma, where they act as a crucial buffer, maintaining the pH of blood. The reversible nature of these reactions means that CO₂ can be efficiently expelled from the lungs during exhalation.

Biochemical reactions

Biochemical reactions involving CO₂ and bicarbonate are pivotal for understanding respiratory physiology and maintaining homeostasis. As CO₂ diffuses out of tissues and into the bloodstream, these reactions regulate not just the transfer of gases but also play a vital role in the acid-base balance of the blood. The main biochemical reaction mediated by carbonic anhydrase can be expressed as follows:
\[ \mathrm{CO}_{2} + \mathrm{H}_{2}\mathrm{O} \leftrightarrow \mathrm{H}_{2}\mathrm{CO}_{3} \leftrightarrow \mathrm{H}^{+} + \mathrm{HCO}_{3}^{-} \] The interconversion between CO₂ and bicarbonate is efficient and rapid, making it responsive to the body's metabolic demands.

Furthermore, the role of carbonic anhydrase is indispensable as it enables the rapid conversion necessary to support continuous respiration. The enzyme accelerates the reaction, making the physiological exchange of gases smooth and uninterruptible. This enzyme's function showcases the elegance and complexity of biochemical systems working seamlessly in the body.