Lecture No 13 LYSOSOME AND MALFUNCTION OF LYSOSOME

Описание: 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)

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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