Problem 14 - Anatomy and Physiology of Animals

Question

Which of the following organelles produces large quantities of ATP when both glucose and oxygen are available to the cell? a. mitochondria b. peroxisomes C. lysosomes d. \(\mathrm{ER}\)

Step-by-Step Solution

Answer

The correct answer is mitochondria.

Step 1: Understanding ATP Production

ATP, or adenosine triphosphate, is the primary energy carrier in cells. Cells produce ATP through cellular respiration, a process that requires glucose and oxygen. This process occurs primarily in a specific organelle.

Step 2: Identifying the Key Organelle

Mitochondria are the organelles responsible for producing ATP through cellular respiration. In the presence of glucose and oxygen, mitochondria generate large amounts of ATP via oxidative phosphorylation, the final stage of cellular respiration.

Step 3: Distractor Analysis

Peroxisomes, lysosomes, and the endoplasmic reticulum (ER) have different primary functions. Peroxisomes are involved in lipid metabolism and detoxification. Lysosomes digest cellular waste and macromolecules. The ER is involved in protein and lipid synthesis, but not in producing ATP.

Step 4: Conclusion

Given that mitochondria are the powerhouses of the cell, generating ATP in the presence of glucose and oxygen, they are the organelles that match the question's criteria.

Key Concepts

ATP production

ATP, or adenosine triphosphate, is vital for cell energy and functions as the main energy currency of cells. This molecule is generated during the process of cellular respiration.
Cellular respiration involves breaking down glucose with oxygen to release energy. This energy is then stored in the bonds of ATP molecules.
ATP production occurs through three major steps: glycolysis, Krebs cycle (also known as the citric acid cycle), and oxidative phosphorylation.

• Glycolysis starts the process by breaking down glucose into pyruvate, producing a small amount of ATP.
• The Krebs cycle processes these molecules further, resulting in the production of electron carriers and more ATP.

The final step, oxidative phosphorylation, is where the majority of ATP is produced.

mitochondria

Often referred to as the powerhouses of the cell, mitochondria play a key role in energy production. These organelles are where the majority of ATP is generated.
Mitochondria have a special structure that allows them to efficiently carry out cellular respiration.
They have two membranes: an inner and an outer membrane. The space between these membranes and within the inner membrane are crucial for ATP production.

• The inner membrane is folded into structures called cristae, which increase its surface area, allowing more space for ATP-producing reactions.
• Inside the inner membrane, several important components for ATP production are housed, including enzymes and proteins involved in the Krebs cycle and oxidative phosphorylation.

By channeling energy through these structures, mitochondria maintain high efficiency in ATP production.

oxidative phosphorylation

Oxidative phosphorylation is the final and most significant stage of ATP production in cellular respiration. It occurs in the inner membrane of mitochondria.
This process involves the electron transport chain and chemiosmosis, both of which are crucial for producing large amounts of ATP.

• The electron transport chain comprises a series of protein complexes that transfer electrons derived from electron carriers like NADH and FADH2. This movement of electrons results in the pumping of protons (H+) across the inner mitochondrial membrane, creating a gradient.
• Through chemiosmosis, this proton gradient drives the synthesis of ATP. As protons flow back across the membrane through ATP synthase, this enzyme catalyzes the conversion of ADP and inorganic phosphate into ATP.

Oxidative phosphorylation efficiently captures energy and results in the production of up to 34 ATP molecules per molecule of glucose, underscoring its importance in cellular energy supply.