In what cellular organelle does cellular respiration occur?
A.
Chloroplast.
B.
Mitochondrion.
C.
Golgi apparatus.
D.
Endoplasmic reticulum.
The correct answer and Explanation is :
The correct answer is B. Mitochondrion.
Cellular respiration is a crucial process for energy production within cells, and it primarily occurs in the mitochondria. Mitochondria are often referred to as the “powerhouses” of the cell due to their role in generating adenosine triphosphate (ATP), which is the primary energy currency of the cell.
The process of cellular respiration involves several stages: glycolysis, the citric acid cycle (or Krebs cycle), and oxidative phosphorylation, which includes the electron transport chain and chemiosmosis. Here’s a brief overview of each stage:
- Glycolysis: This process takes place in the cytoplasm of the cell, not in the mitochondria. Glycolysis breaks down glucose into pyruvate, producing a small amount of ATP and NADH (a carrier of electrons).
- Citric Acid Cycle (Krebs Cycle): The pyruvate produced in glycolysis is transported into the mitochondria, where it is converted into acetyl-CoA. This acetyl-CoA then enters the citric acid cycle, which occurs in the mitochondrial matrix. This cycle produces ATP, NADH, and FADH2, which are essential for the next stage of respiration.
- Oxidative Phosphorylation: This stage occurs across the inner mitochondrial membrane and involves the electron transport chain and chemiosmosis. Electrons from NADH and FADH2 are transferred through a series of protein complexes embedded in the inner mitochondrial membrane, creating a proton gradient. This gradient drives the synthesis of ATP by ATP synthase, a process known as chemiosmosis.
The mitochondrion’s structure is highly adapted to its role in cellular respiration. It has a double membrane; the inner membrane is folded into cristae to increase surface area for the electron transport chain. The space inside the inner membrane is called the mitochondrial matrix, where the citric acid cycle takes place.
In summary, the mitochondrion is the organelle where cellular respiration occurs, enabling cells to convert nutrients into ATP, essential for various cellular functions.