Problem 81 - Objective Biology for NEET

Question

The reaction of Kreb's cycle take place (a) In cytoplasm (b) In endoplasmic reticulum (c) In matrix of mitochondria (d) On the surface of mitochondrion

Step-by-Step Solution

Answer

The Kreb's cycle takes place in the matrix of the mitochondria.

Step 1 Recall the structure of a cell

Cells are composed of various structures including the cytoplasm, endoplasmic reticulum, and mitochondria. The cytoplasm is the internal fluid of the cell. The endoplasmic reticulum is involved in protein and lipid synthesis. Mitochondria, often referred to as the powerhouse of the cell, are involved in energy production.

Step 2 Understand the Kreb's Cycle

The Kreb's cycle, also known as the citric acid cycle or the tricarboxylic acid cycle, is a series of chemical reactions used by all aerobic organisms to release stored energy. This occurs through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins into ATP.

Step 3 Link the Kreb's Cycle to the correct cell structure

Given that the Kreb's cycle is involved in energy production, it makes sense that it would occur in the mitochondria, which are the energy-producing structures in a cell. More specifically, the Kreb's cycle occurs in the matrix of the mitochondria, which is the space within the inner membrane of the mitochondria. Therefore, (c) In matrix of mitochondria is the correct choice.

Key Concepts

Mitochondria

Mitochondria are fascinating structures often titled the "powerhouse of the cell." These organelles play a critical role in producing energy for the cell. Located within a double membrane, mitochondria have an inner membrane that is folded into structures known as cristae.
These folds increase the surface area, allowing for more space to implement reactions necessary for energy production. Inside the innermost part of a mitochondrion is the matrix, which houses the enzymes necessary for the Kreb's Cycle.

• Matrix: The fluid-filled space where the Kreb's cycle takes place, converting energy into ATP.
• Cristae: Provides increased surface area for ATP production through electron transport chain and oxidative phosphorylation.

Understanding the mitochondrial structure is key to grasping how energy is produced and managed within a cell.

Energy Production

Energy production in cells is a vital process that powers cellular functions. Among the crucial pathways, the Kreb's Cycle stands out as a central series of reactions.
Taking place in the matrix of the mitochondria, this cycle breaks down nutrients to produce high-energy molecules like ATP, which cells use to perform various tasks.

• Kreb’s Cycle: Involves nine enzymatic reactions that process acetyl-CoA, release carbon dioxide, and capture energy-rich electrons.
• Electron Transport Chain: Follows the Kreb's cycle and occurs on the cristae membranes, converting energy from electrons into ATP.

Energy production doesn’t end with the Kreb's cycle. It connects to other pathways, ensuring efficient conversion of food into usable energy.

Cell Structure

The structure of cells is beautifully complex, comprising various organelles, each with distinct functions. While the entire cell is involved in sustaining life, specific structures are integral to energy processes.
The mitochondrion, with its matrix and cristae, is pivotal for processes like the Kreb's cycle and oxidative phosphorylation, crucial for energy production.

• Cytoplasm: Gel-like substance where initial stages of glucose breakdown happen before entering the mitochondria.
• Endoplasmic Reticulum: Although less involved in direct energy production, this organelle is essential for protein and lipid synthesis.

Overall, each part of a cell's structure plays a role, aiding in the cell's primary goal: sustaining life and energy flow.