Lecture No 13 LYSOSOME AND MALFUNCTION OF LYSOSOME скачать в хорошем качестве

Lecture No 13 LYSOSOME AND MALFUNCTION OF LYSOSOME

Lysosome A lysosome is a small, membrane-bound organelle found mainly in eukaryotic animal cells. It is often called the “suicide bag” or “digestive system” of the cell. Structure • Surrounded by a single membrane • Contains hydrolytic (digestive) enzymes such as proteases, lipases, nucleases, and carbohydrases • Has an acidic interior (pH ~4.5–5), maintained by proton pumps, which is optimal for enzyme activity Functions • Intracellular digestion: Breaks down food particles, organelles, and macromolecules • Autophagy: Destroys worn-out or damaged organelles • Autolysis: Can digest the entire cell during programmed cell death • Defense: Destroys pathogens like bacteria and viruses • Recycling: Reuses breakdown products (amino acids, sugars, fatty acids) ⸻ Malfunction of Lysosome When lysosomes do not work properly, digestive enzymes fail to break down substances, leading to their accumulation inside cells. This causes a group of disorders known as lysosomal storage diseases (LSDs). Causes of Malfunction • Genetic mutations affecting lysosomal enzymes • Defective transport proteins or membrane proteins • Failure to maintain acidic pH Effects • Accumulation of undigested materials inside lysosomes • Cell enlargement and dysfunction • Tissue and organ damage, especially in brain, liver, spleen, and muscles • Can lead to cell death Examples of Lysosomal Storage Diseases • Tay-Sachs disease – accumulation of GM2 gangliosides (affects nervous system) • Gaucher disease – accumulation of glucocerebrosides • Pompe disease – accumulation of glycogen in muscles • Niemann-Pick disease – accumulation of