Problem 50 - Objective Biology for NEET

Question

Oxidative phosphorylation occurs in (a) Mitochondria (b) Chloroplast (c) Cytoplasm (d) All of these

Step-by-Step Solution

Answer

Oxidative phosphorylation occurs in Mitochondria

Step 1: Understanding the process of Oxidative phosphorylation

Oxidative phosphorylation is the metabolic pathway in which cells use enzymes to oxidize nutrients, releasing the chemical energy of molecular oxygen, and this in turn is used to produce ATP. It is a crucial part of cellular respiration, the process that generates energy for cell functions.

Step 2: Identifying the location of Oxidative phosphorylation

The location where this process occurs is important since it defines where the energy-making process of a cell takes place. Oxidative phosphorylation mainly occurs inside a cell's mitochondria. Mitochondria are called the powerhouses of the cell because they generate most of the cell's ATP via oxidative phosphorylation.

Step 3: Matching with the options

From our understanding of where oxidative phosphorylation takes place, we can go through each given option and choose the one that matches our understanding. Among the choices, Mitochondria is the correct answer.

Key Concepts

Mitochondria

Mitochondria are often referred to as the powerhouses of the cell due to their critical role in energy production. These double-membraned organelles are found in eukaryotic cells and play a pivotal role in producing adenosine triphosphate (ATP), the energy currency of the cell.

They house the electron transport chain, a series of protein complexes that facilitate oxidative phosphorylation. Inside the inner membrane of mitochondria, electrons are transferred through these proteins while protons are pumped into the intermembrane space, creating a proton gradient.

This gradient is then used by ATP synthase, a key enzyme, to produce ATP from adenosine diphosphate (ADP) and inorganic phosphate (Pi). Mitochondria's unique structure allows them to efficiently convert energy from nutrients into a form that can be used by cells, highlighting their importance in cellular energy metabolism.

Cellular Respiration

Cellular respiration is the multi-step process by which cells convert nutrients into energy. It consists of three main stages: Glycolysis, the Citric Acid Cycle (also known as the Krebs cycle), and Oxidative Phosphorylation.

• Glycolysis occurs in the cytoplasm and breaks down glucose into two molecules of pyruvate, generating a small amount of ATP.
• The Citric Acid Cycle takes place in the mitochondrial matrix, oxidizing acetyl-CoA to CO₂ and transferring electrons to carriers NAD⁺ and FAD, forming NADH and FADH₂.
• Oxidative Phosphorylation is the final stage, where NADH and FADH₂ donate electrons to the electron transport chain, leading to ATP production in the mitochondria.

Each stage of cellular respiration is vital for the efficient conversion of energy from nutrient molecules into ATP, the form of energy cells can use to perform various functions.

ATP Production

ATP production is the ultimate goal of oxidative phosphorylation, as ATP serves as the primary energy carrier in cells. During oxidative phosphorylation, the process begins with electrons being transferred from NADH and FADH₂ to the electron transport chain in the mitochondria.

This chain consists of multiple protein complexes that pass electrons down a series of redox reactions, capturing energy to pump protons across the mitochondrial inner membrane, establishing a strong proton gradient.

As protons flow back into the mitochondrial matrix through ATP synthase, the enzyme catalyzes the phosphorylation of ADP to ATP. This conversion captures chemical energy in a form that the cell can readily utilize to power various activities, such as muscle contraction, neuron firing, and biosynthesis pathways, making ATP production fundamental to sustaining life.