Question

Assertion: Kerb's cycle is referred as aerobic respiration Reason: In Kerb's cycle glucose is completely oxidised to \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\)

Short answer

Yes, the assertion is correct, and the reason provided is valid. The Kerb's cycle is, indeed, a part of aerobic respiration as it is where the complete oxidation of glucose to CO2 and H2O happens, just as is described in the definition of aerobic respiration.

Step-by-step solution

Define the Kerb's cycle

The Kerb's cycle, also known as the citric acid cycle or the tricarboxylic acid cycle, is a crucial part of cellular respiration that takes place in the mitochondria. It is a cycle of enzyme-catalyzed chemical reactions where energy is produced through the oxidation of acetyl-CoA into CO2 and H2O.

Define aerobic respiration

Aerobic respiration is a metabolic process in which glucose is completely oxidised into carbon dioxide (CO2) and water (H2O) in the presence of oxygen. The energy released from these reactions is used by cells to perform their regular functions. Aerobic respiration is a three-step process consisting of glycolysis, the Kerb's cycle, and electron transport.

Associate Kerb's cycle with Aerobic respiration

Assessing the definitions of both Kerb's cycle and aerobic respiration, we can conclude that the Kerb's cycle is indeed a part of aerobic respiration. The fundamental reason for this is that in the Kerb's cycle, glucose is entirely oxidised to CO2 and H2O - a process occurring in aerobic respiration.

Key concepts

Aerobic Respiration

Aerobic respiration is a powerhouse process that is essential for life. It's like unlocking the energy treasure trapped in food. Think of aerobic respiration as a meticulous chemical transformation within our cells that turns oxygen and nutrients, primarily glucose, into a bounty of energy. This energy is measured in ATP (adenosine triphosphate), the small energy currency of the cell that powers virtually every cellular activity.

In the presence of oxygen, aerobic respiration goes through three major phases: glycolysis in the cytosol, the Kreb's cycle in the mitochondria, and finally, the electron transport chain, also housed in the mitochondria. Imagine aerobic respiration as a relay race where glucose, the baton of energy, is passed from one process to another until energy is released.

Cellular Respiration

Cellular respiration is the overall name given to the process by which cells harvest energy from food. It's not just a one-step reaction but a series of complex processes that extract ATP from the breakdown of energy-rich molecules like glucose.

As the central hub of metabolic energy, cellular respiration can occur in two ways: aerobically with oxygen, or anaerobically without oxygen. While aerobic respiration yields a high amount of ATP, anaerobic respiration is less efficient but kicks in when oxygen levels are low. In aerobic conditions, when oxygen acts as the final electron acceptor, procedures like the Kreb's Cycle and oxidative phosphorylation are where the excitement happens, leading to the most significant energy payoff.

Citric Acid Cycle

Diving into the heart of the mitochondria, the Citric Acid Cycle, also known as Kreb's Cycle, is a series of chemical reactions used by all aerobic organisms to generate energy. It is a part of the majestic process where living things convert the food they eat into the energy they need. After glucose is broken down into the molecule acetyl-CoA during the prep phase, it enters this cycle.

The cycle churns through eight steps, each meticulously catalyzed by a specific enzyme. At every turn, it snips off electrons and protons to help power ATP synthesis and also produces carbon dioxide as a waste product. All this bustling biochemical activity only kicks into gear in the presence of oxygen, which is why the Kreb's Cycle is a star player in aerobic respiration.

Enzyme-Catalyzed Reactions

Critical Catalysts

Life would be unbearably slow without enzymes. These biological catalysts are like elite workers on an assembly line, accelerating chemical reactions that would otherwise drag on at an impractical pace. The Kreb's Cycle is a showcase of enzyme-catalyzed reactions, with each step sped up by a specific enzyme. Like a lock and key, substrates bind with their respective enzymes, leading to molecular transformations that are fundamental to life.

Enzymes don't just make things faster; they also ensure that reactions happen in a controlled and orderly manner, preventing chaos within the cell. Without these diligent facilitators, critical life-sustaining processes like the Kreb's Cycle wouldn't be possible.

Mitochondria

The Powerhouse of the Cell

Within our cells, mitochondria are the designated energy factories. Elegant yet complex, mitochondria are unique cell organelles that host key parts of aerobic respiration, including the Kreb's Cycle and electron transport chain. They boast their own DNA, can multiply independently, and are shaped perfectly to maximize their efficiency in energy production.

Apart from energy conversion, mitochondria are also implicated in tasks like cell signaling, cellular differentiation, and even cell death, making them vital beyond just energy production. The inner folds, or cristae, greatly increase the surface area inside the organelle, gearing up the mitochondria for optimum performance.

Acetyl-CoA Oxidation

Acetyl-CoA stands as the key that ignites the engine of the Kreb's Cycle. It is the condensed form of carbon derived from carbohydrates, fats, and proteins—practically packaged for entry into the cycle. The oxidation of acetyl-CoA is a critical step, starting the cycle by combining with a four-carbon molecule to form citrate, setting in motion a cascade of energy-releasing reactions.

This process not only yields essential compounds like ATP, NADH, and FADH2 which will later fuel the electron transport chain but also releases CO2, a byproduct of oxidation. Acetyl-CoA is central to energy metabolism, linking various nutritional components to the energy-producing pathways in our cells.

Biochemistry for NEET

For students aspiring to crack the National Eligibility cum Entrance Test (NEET), understanding the intricacies of biochemistry is non-negotiable. Topics like the Kreb's Cycle are not only fascinating in illustrating how life derives energy but are also crucial for the NEET exam. A robust grasp of such biochemistry concepts allows students to tackle questions regarding metabolic pathways, the role of enzymes, and energy production within cells confidently.

Future physicians are required to understand these biochemical pathways in depth, as they form the foundation for human physiology and are integral to diagnosing and treating metabolic disorders. By studying these systems carefully, NEET aspirants equip themselves with knowledge that's essential for both the exam and their future medical careers.