Lysosomes and Peroxisomes

endomembrane system
hydrolytic enzyme

Cell Biology

Lysosomes and peroxisomes are both organelles responsible for digesting matter within cells. Lysosomes are vesicles that contain hydrolytic enzymes to aid in cell digestion. They participate in processes such as autophagy, where they break down the cell's own organelles, and phagocytosis, where they metabolize material from the environment, like pathogens. Lysosomes can also trigger cell death through a process called autolysis by releasing their enzymes into the rest of the cell.

Peroxisomes, on the other hand, are organelles that break down molecules through a process called oxidation. Unlike lysosomes, they are not part of the endomembrane system. Peroxisomes contain enzymes that form hydrogen peroxide (H₂O₂) from substrates, which can be toxic. However, they also have special enzymes that break toxic H₂O₂ into nontoxic molecules like water and sometimes oxygen. Peroxisomes are involved in the detoxification of harmful substances and the breakdown of fatty acids, which will eventually be used to produce energy for the cell.

Lesson Outline

<ul> <li>Lysosomes and Peroxisomes - Functions</li> <ul> <li>Lysosomes</li> <ul> <li>Part of the endomembrane system</li> <li>Contain hydrolytic enzymes for cell digestion</li> <li>Engulf and break down cellular material and pathogens</li> <li>Autophagy - breaking down of a cell's own organic materials</li> <li>Phagocytosis - metabolizing external material such as pathogens, cellular debris, etc.</li> <li>Autolysis - releasing hydrolytic enzymes into the rest of the cell to destroy it (triggered when a cell is injured or diseased)</li> </ul> <li>Peroxisomes</li> <ul> <li>Not part of the endomembrane system</li> <li>Break down molecules through oxidation</li> <li>Contain enzymes that form hydrogen peroxide (H₂O₂)</li> <li>Enzymes break down toxic H₂O₂ into non-toxic molecules (water and oxygen)</li> <li>Detoxification of harmful substances in certain cells</li> <li>Breakdown of fatty acids for energy production</li> </ul> </ul> </ul>

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What is the main difference between lysosomes and peroxisomes in terms of their function within a cell?

Lysosomes are responsible for breaking down and recycling cellular waste and foreign material via processes such as autophagy, cell digestion, and phagocytosis. They contain hydrolytic enzymes that aid in the break-down process. Peroxisomes, on the other hand, are responsible for the breakdown of fatty acids and detoxification of harmful substances through oxidation reactions. Both organelles play vital roles in maintaining cellular homeostasis.

How do lysosomes and peroxisomes relate to the endomembrane system in eukaryotic cells?

The endomembrane system is an interconnected network of membrane-bound structures that function in protein synthesis, lipid metabolism, and detoxification processes within eukaryotic cells. Lysosomes are part of this system, while peroxisomes are not. Lysosomes use their connection to this sytem to coordinate their functions with other organelles within the endomembrane system, like the endoplasmic reticulum and Golgi apparatus.

What is autophagy?

Autophagy is a cellular process in which damaged or dysfunctional cellular components are engulfed by autophagosomes, which later fuse with lysosomes. This process allows lysosomes to degrade and recycle these components, maintaining cellular homeostasis and preventing the accumulation of damaged proteins and organelles. Through this mechanism, lysosomes contribute to the overall health and function of the cell and aid in cellular adaptation to changing conditions, such as nutrient deprivation or stress.

What role do hydrolytic enzymes play in the function of lysosomes?

Hydrolytic enzymes, also known as hydrolases, are responsible for breaking down various biomolecules within the lysosome. These enzymes use water to catalyze the breakdown of a wide range of substrates, including proteins, nucleic acids, carbohydrates, and lipids. Because lysosomes are responsible for digesting cellular waste and foreign material, the presence of hydrolytic enzymes is essential for effective degradation and recycling of these materials within the cell.

How does oxidation function within peroxisomes?

Oxidation is a chemical process in which a molecule loses one or more electrons. Peroxisomes contain enzymes that catalyze oxidation reactions, which allows them to break down fatty acids and neutralize reactive oxygen species, such as hydrogen peroxide. By carrying out these reactions, peroxisomes contribute to cellular energy production, lipid metabolism, and the detoxification of harmful substances, ensuring the cell maintains proper function and homeostasis.