Problem 88 - Objective Biology for NEET

Question

The last or terminal cytochrome in respiratory chain is (a) Cyt b (b) Cyt a \(_{3}\) (c) Cyt a (d) Cyt c

Step-by-Step Solution

Answer

(b) Cyt a\(_{3}\) is the terminal or last cytochrome in the respiratory chain.

Step 1: Understanding the Electron Transport Chain

A cytochrome is a molecule in the electron transport chain that accepts and releases electrons in the sequence of reactions. The final or terminal cytochrome has a critical role in the process of cellular respiration. It's important to remember the structure and proceeding of the electron transport chain.

Step 2: Identifying the Terminal Cytochrome

The final cytochrome in the electron transport chain is Cyt a\(_{3}\). The electron transported by the chain is transferred to an oxygen molecule by Cytochrome a3. This, in turn, results in water.

Step 3: Choosing the Correct Answer

With this knowledge, the appropriate option to this multiple choice question is (b) Cyt a\(_{3}\).

Key Concepts

Electron Transport Chain

The Electron Transport Chain (ETC) is a complex series of proteins and other molecules embedded in the inner mitochondrial membrane. These proteins, including a variety known as cytochromes, play a critical role in converting nutrients into adenosine triphosphate (ATP), the energy currency of the cell.

During this process, electrons are passed from molecule to molecule and ultimately transferred to oxygen, which forms water. Each step in the ETC helps to build up an electrochemical gradient, which is used by another protein complex, ATP synthase, to generate ATP.

It's a bit like a relay race, where electrons 'pass the baton' down the line of cytochromes until reaching the finish line, which in the cellular world is the terminal cytochrome. The efficient handoff of electrons is essential to maintain the flow of energy and the production of ATP.

Cellular Respiration

Cellular respiration is a set of metabolic reactions that take place in the cells of organisms to convert biochemical energy from nutrients into ATP, releasing waste products in the process. This crucial activity occurs in every cell and is fundamental for life.

The process consists of three main stages: glycolysis, the Krebs cycle, and the electron transport chain. The ETC is the final destination in the journey of electrons that began in the initial stages of cellular respiration. It's the stage where the most ATP is generated, capitalizing on the energy carried by electrons.

As students delve into understanding cellular respiration, it's important to conceptualize it not just as a single event but as a marathon that comprises various steps, with the ETC being the last leg where the energy sprint pays off.

Cytochrome a3

Cytochrome a3, also known as Cytochrome c oxidase, is a critical component of the Electron Transport Chain and the terminal cytochrome in this energy-yielding relay. It serves as the final electron acceptor and is responsible for catalyzing the reduction of oxygen to water.

This enzyme has a heme-iron center where oxygen binds and is reduced – a vital step because without the proper functioning of Cytochrome a3, the ETC would come to a halt and no further ATP could be generated. It is like the last gatekeeper ensuring that the cellular power plant achieves its final energy output.

Understanding the role of Cytochrome a3 helps students appreciate how each component of the ETC contributes to the larger goal of energy production, showcasing the intricate symphony of reactions that sustain life at the cellular level.