How do lysosomes remove dead cells?

Lysosomes remove dead cells by degrading their components into basic building blocks after the dead cell is engulfed by a macrophage.

Here's a breakdown of the process:

1. "Find Me" Signal: Dead cells release signals that attract immune cells, particularly macrophages.

2. Engulfment: Macrophages recognize "eat me" signals on the surface of the dead cell and engulf it through a process called phagocytosis. This creates a vesicle called a phagosome.

3. Lysosome Fusion: The phagosome containing the dead cell fuses with a lysosome, forming a phagolysosome.

4. Degradation by Lysosomal Enzymes: Lysosomes contain a variety of hydrolytic enzymes (acid hydrolases) that break down different types of macromolecules. Within the phagolysosome, these enzymes degrade the dead cell's components into their basic constituents:

   • Proteins are broken down into amino acids.
   • Nucleic acids (DNA and RNA) are broken down into nucleotides.
   • Lipids are broken down into fatty acids.
   • Polysaccharides are broken down into monosaccharides (simple sugars).

5. Recycling and Waste Removal: The resulting amino acids, nucleotides, fatty acids, and monosaccharides are then transported out of the lysosome and recycled by the cell to build new molecules. Any undigested waste products remain within the lysosome. These residual bodies can either be exocytosed (released from the cell) or accumulate within the cell.

In essence, lysosomes act as the cellular "recycling centers" for dead cells, breaking them down into their fundamental components for reuse.