Lecture No 14 PEROXSOME AND GLYXISOME

Описание: Peroxisome

A peroxisome is a small, membrane-bound organelle found in eukaryotic cells (both plant and animal cells). It is mainly involved in oxidative reactions.

Structure
• Surrounded by a single membrane
• Contains oxidative enzymes such as oxidases and catalase
• Does not contain DNA or ribosomes
• Enzymes are synthesized in the cytoplasm and imported into the peroxisome

Functions
• Breakdown of fatty acids (β-oxidation), especially very long-chain fatty acids
• Detoxification of harmful substances like alcohol and hydrogen peroxide
• Metabolism of hydrogen peroxide (H₂O₂)
• Oxidases produce H₂O₂
• Catalase converts H₂O₂ into water and oxygen
• In plants: role in photorespiration

Importance

Peroxisomes protect cells from oxidative damage and help maintain metabolic balance.

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Glyoxysome

A glyoxysome is a specialized type of peroxisome found mainly in germinating seeds of plants. It plays a crucial role in fat metabolism during seed germination.

Structure
• Surrounded by a single membrane
• Contains enzymes of fatty acid β-oxidation
• Contains key enzymes of the glyoxylate cycle (e.g., isocitrate lyase, malate synthase)

Functions
• Converts stored fats into carbohydrates
• Enables synthesis of glucose from fatty acids
• Provides energy and carbon skeletons for the growing seedling before photos