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Lysosomes

lysosomes

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Lysosomes

  1. 1. Lysosomes CELL BIOLOGY PRESENTED BY:- NEHA MAYACH NEHA MAYACH M.SC LIFE SCIENCE 1
  2. 2. Contents  Introduction  Lysosomal Enzymes  Site of Lysosome synthesis  Features  Pathways leading to lysosomes  Process for digestion 1. Phagocytosis 2. Endocytosis 3. Autophagy  Types of Lysosomes  Diseases  Some facts 2
  3. 3. INTRODUCTION What are Lysosomes…?  Lysosomes are spherical organelle that contain enzymes acid hydrolases. They break up food so it is easier to digest. They are found in animal cells, while in yeast and plants the same roles are performed by lytic vacuoles.  Discovered by De Duve in 1955.Named also.  1st electron micrograph by Novikoff.  In 1974 De Duve got nobel prize. 3
  4. 4.  Lysosomes are common in animal cells but rare in plant cells contain hydrolytic enzymes necessary for intracellular digestion.  The size of lysosomes varies from 0.1–0.8 μm. They are larger in phagocytes(WBC) 0.8-2 µm. 4
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  6. 6.  All these hydrolytic enzymes are produced in the endoplasmic reticulum, and to some extent in cytoplasm are transported and processed through the Golgi apparatus.  and through golgi apparatus they pinch off as single membrane vesicles. 6
  7. 7.  It is called : "The Police Force of the Cell" "suicide bags“ “Stomach of cell” 7
  8. 8. SITE OF SYNTHESIS  Lysosomes are produced in the Golgi Apparatus 8
  9. 9. FEATURES  A lysosome is a membrane bag containing digestive enzymes  to digest food, the lysosome membrane fuses with the membrane of a food vacuole and squirts the enzymes inside.  The digested food can then diffuse through the vacuole membrane and enter the cell to be used for energy or growth. 9
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  11. 11.  Lysosomes are the cell’s garbage disposal system. They are used for the digestion of macromolecules from 1.Phagocytosis (ingestion of larger extracellular material, like foreign invading microbes) . 11 2.Endocytosis (ingestion of macromolecules where receptor proteins are recycled from the cell surface), and
  12. 12. 3.Autophagy (wherein old or unneeded organelles or proteins, or microbes that have invaded the cytoplasm are delivered to the lysosome). Autophagy may also lead to autophagic cell death, a form of programmed self-destruction, or autolysis, of the cell, which means that the cell is digesting itself. 12
  13. 13. 13 TYPES OF LYSOSOMES
  14. 14.  Lysosomes pick up foreign invaders such as bacteria, food and old organelles and break them into small pieces that can hopefully be used again. (Recycling unit of cell)  In human liver cells it is calculated that at least one mitochondria undergoes autophagy every 10 minutes. This reflects the highly active nature of the liver as an organ and it's need for a constant supply of fresh organelles. The electron micrograph below shows a lysosome in the process of destroying a membrane bound mitochondria. 14
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  16. 16. Tay Sach’s Disease 16 • A lysosomal storage disease(LSD) – Due to a mutation in lysosomal enzymes B-N-hexosaminidase-A* • Accumulations of un-degraded glycolipid (Ganglioside) within lysosomes in brain NERVE CELL • Found in neurons of CNS • Diagnostic feature-Cherry red spot on Retina(By Tay-name of scientist) • Autosomal recessive genetic disorder
  17. 17.  Pompe’s Disease- lysosomes of some people lack enzymes for digestion of Glycogen. In such persons excessive storage of glycogen occurs in liver.  Lysosomal enzymes are synthesized in the cytosol and the endoplasmic reticulum, where they receive a mannose-6-phosphate tag that targets them for the lysosome.  If the lysosomal enzymes do not reach the target it causes inclusion- cell disease, resulting in accumulation of waste within these organelles. 17
  18. 18. FACTS  The only thing that keeps the cell itself from being digested is the membrane surrounding the lysosomes.  Highly polymorphic cell organelle.  Lyosomes of Osteoclast cells(bone eating cells) dissolves unwanted part of bones.  Crinophagy - Excessive secretion of hormone in endocrine gland may be digested by lysosomes. 18
  19. 19.  These enzymes work only at low pH (highly acidic) levels.  However because they can only work at low pH levels and the rest of the cell has a neutral pH level, they can be neutralized if they accidentally escape from the lysosome 19
  20. 20.  In white blood cells that eat bacteria, lysosome contents are carefully released into the vacuole around the bacteria and serve to kill and digest those bacteria. Uncontrolled release of lysosome contents into the cytoplasm can also cause cell death (necrosis). 20
  21. 21. THANK YOU 21

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