Lecture 10 - Lysosome | Cell Biology- Botany PDF Download

 Page 1


Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
 
Lesson: Lysosome 
Lesson Developer: Rina Majumdar 
College/ Department: Botany Department, Maitreyi College, 
University of Delhi 
  
Page 2


Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
 
Lesson: Lysosome 
Lesson Developer: Rina Majumdar 
College/ Department: Botany Department, Maitreyi College, 
University of Delhi 
  
Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
Table of Contents      
 
Chapter: Lysosome 
? Introduction  
? Structure  
? Role  
? Biogenesis  
? Lysosomal storage diseases (LSD)  
? Summary  
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
 
 
 
 
 
 
 
 
 
Page 3


Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
 
Lesson: Lysosome 
Lesson Developer: Rina Majumdar 
College/ Department: Botany Department, Maitreyi College, 
University of Delhi 
  
Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
Table of Contents      
 
Chapter: Lysosome 
? Introduction  
? Structure  
? Role  
? Biogenesis  
? Lysosomal storage diseases (LSD)  
? Summary  
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
 
 
 
 
 
 
 
 
 
Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
Introduction      
Nobel Prize laureate Christian de Duve and his co-workers discovered a new microbody in 
animal cells in late 1950s, which was named lysosome.  Experiments to identify the 
localization of the two enzymes glucose-6-phosphatase and acid phosphatase in liver tissue 
homogenates by differential centrifugation clearly indicated that acid phosphatase enzyme 
was located in a new class of particles never reported before.  In addition to acid 
phosphatase these new organelles contained several other hydrolytic enzymes including 
proteases, lipases,ß-glucoronidases, ribonucleases, deoxyribonucleases all of which have an 
apparent role in cellular lysis.  C. de Duve named this organelle lysosome for their role in 
lysis. The organelle contains approximately 50 different types of hydrolyzing enzymes. 
 
Figure:Under electron microscope, lysosomes are found to be of the size of mitochondrion, 
are small electron dense, nearly circular, single membrane structure with the diameter 
varies from 0.1-0.8 ?m.  
Source:http://www.dematice.org/ressources/PCEM1/Histologie/P1_histo_009/Web/res/figur
e18.jpg 
To distinguish lysosome from other small, single membrane electron dense particles within 
the cells, in 1952 G.Gomori introduced modified cytochemical procedures and identified the 
lysosome based on high acid phosphatase content, which is the marker enzyme for the 
organelle. 
Page 4


Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
 
Lesson: Lysosome 
Lesson Developer: Rina Majumdar 
College/ Department: Botany Department, Maitreyi College, 
University of Delhi 
  
Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
Table of Contents      
 
Chapter: Lysosome 
? Introduction  
? Structure  
? Role  
? Biogenesis  
? Lysosomal storage diseases (LSD)  
? Summary  
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
 
 
 
 
 
 
 
 
 
Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
Introduction      
Nobel Prize laureate Christian de Duve and his co-workers discovered a new microbody in 
animal cells in late 1950s, which was named lysosome.  Experiments to identify the 
localization of the two enzymes glucose-6-phosphatase and acid phosphatase in liver tissue 
homogenates by differential centrifugation clearly indicated that acid phosphatase enzyme 
was located in a new class of particles never reported before.  In addition to acid 
phosphatase these new organelles contained several other hydrolytic enzymes including 
proteases, lipases,ß-glucoronidases, ribonucleases, deoxyribonucleases all of which have an 
apparent role in cellular lysis.  C. de Duve named this organelle lysosome for their role in 
lysis. The organelle contains approximately 50 different types of hydrolyzing enzymes. 
 
Figure:Under electron microscope, lysosomes are found to be of the size of mitochondrion, 
are small electron dense, nearly circular, single membrane structure with the diameter 
varies from 0.1-0.8 ?m.  
Source:http://www.dematice.org/ressources/PCEM1/Histologie/P1_histo_009/Web/res/figur
e18.jpg 
To distinguish lysosome from other small, single membrane electron dense particles within 
the cells, in 1952 G.Gomori introduced modified cytochemical procedures and identified the 
lysosome based on high acid phosphatase content, which is the marker enzyme for the 
organelle. 
Lysosome 
Institute of Lifelong Learning, University of Delhi 
Structure 
The lysosomes are bound by a single membrane. The lysosomal membrane separates the 
hydrolytic enzymes from the rest of the cell thus protecting the cell from these enzymes. 
Highly glycosylated integral proteins present in the lysosome membrane protect the 
membrane from the attack by the enclosed enzymes. 
The lysosomal enzymes are active at low pH and have a requirement of an acidic pH (4.5 or 
less) for their optimal activity.  Hence, unlike the cytosolic and most other organelle 
enzymes which require a near neutral pH, all the lysosomal enzymes are acidhydrolases.  
The internal compartment of the lysosome providesthe low pH.The unique property 
of the lysosome membrane, is to maintain its internal acidic pH by actively accumulating H
+
 
ions (protons) with the help of a V-type proton pump.  The high internal proton 
concentration is regulated by a proton transporter (H
+
-ATPase) located in the organelles 
boundary membrane, which actively transports protons from the cytosol there by 
maintaining the near neutral pH of the cytoplasm and a highly acidic pH within the 
organelle.  
 
Figure: The lysosome has an acidic pH because of the pumping of protons by a membrane 
bound proton pump that imports protons from the cytosol. The enzymes that are present in 
the lysosome are active at low pH. 
Source: ILLL Inhouse 
Table Enzymes present in lysosome 
Source: Author 
Page 5


Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
 
Lesson: Lysosome 
Lesson Developer: Rina Majumdar 
College/ Department: Botany Department, Maitreyi College, 
University of Delhi 
  
Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
Table of Contents      
 
Chapter: Lysosome 
? Introduction  
? Structure  
? Role  
? Biogenesis  
? Lysosomal storage diseases (LSD)  
? Summary  
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
 
 
 
 
 
 
 
 
 
Lysosome 
Institute of Lifelong Learning, University of Delhi 
 
Introduction      
Nobel Prize laureate Christian de Duve and his co-workers discovered a new microbody in 
animal cells in late 1950s, which was named lysosome.  Experiments to identify the 
localization of the two enzymes glucose-6-phosphatase and acid phosphatase in liver tissue 
homogenates by differential centrifugation clearly indicated that acid phosphatase enzyme 
was located in a new class of particles never reported before.  In addition to acid 
phosphatase these new organelles contained several other hydrolytic enzymes including 
proteases, lipases,ß-glucoronidases, ribonucleases, deoxyribonucleases all of which have an 
apparent role in cellular lysis.  C. de Duve named this organelle lysosome for their role in 
lysis. The organelle contains approximately 50 different types of hydrolyzing enzymes. 
 
Figure:Under electron microscope, lysosomes are found to be of the size of mitochondrion, 
are small electron dense, nearly circular, single membrane structure with the diameter 
varies from 0.1-0.8 ?m.  
Source:http://www.dematice.org/ressources/PCEM1/Histologie/P1_histo_009/Web/res/figur
e18.jpg 
To distinguish lysosome from other small, single membrane electron dense particles within 
the cells, in 1952 G.Gomori introduced modified cytochemical procedures and identified the 
lysosome based on high acid phosphatase content, which is the marker enzyme for the 
organelle. 
Lysosome 
Institute of Lifelong Learning, University of Delhi 
Structure 
The lysosomes are bound by a single membrane. The lysosomal membrane separates the 
hydrolytic enzymes from the rest of the cell thus protecting the cell from these enzymes. 
Highly glycosylated integral proteins present in the lysosome membrane protect the 
membrane from the attack by the enclosed enzymes. 
The lysosomal enzymes are active at low pH and have a requirement of an acidic pH (4.5 or 
less) for their optimal activity.  Hence, unlike the cytosolic and most other organelle 
enzymes which require a near neutral pH, all the lysosomal enzymes are acidhydrolases.  
The internal compartment of the lysosome providesthe low pH.The unique property 
of the lysosome membrane, is to maintain its internal acidic pH by actively accumulating H
+
 
ions (protons) with the help of a V-type proton pump.  The high internal proton 
concentration is regulated by a proton transporter (H
+
-ATPase) located in the organelles 
boundary membrane, which actively transports protons from the cytosol there by 
maintaining the near neutral pH of the cytoplasm and a highly acidic pH within the 
organelle.  
 
Figure: The lysosome has an acidic pH because of the pumping of protons by a membrane 
bound proton pump that imports protons from the cytosol. The enzymes that are present in 
the lysosome are active at low pH. 
Source: ILLL Inhouse 
Table Enzymes present in lysosome 
Source: Author 
Lysosome 
Institute of Lifelong Learning, University of Delhi 
Enzymes Substrate 
Proteases and peptidases 
? Cathepsin A, B, C, D, E 
? Collagenase 
? Arylamidase 
? Peptidase 
Nucleases 
? Acid ribonuclease 
? Acid deoxyribonuclease 
Phosphatases 
? Acid phosphatases 
? Phosphodiesterase 
? Phosphatidic acid phosphatase 
Enzymes acting on carbohydrate chains 
of glycoproteins and glycolipids 
? ßGalactosidase 
? Acetylhexosaminidase 
? ßGlucosidase 
? aGlucosidase 
? aMannosidase 
? Sialidase 
Enzymes acting on glycosaminoglycans 
? Lysozymes 
 
Various proteins and peptides 
Collagen 
Amino acid arylamides 
Peptides 
 
RNA 
DNA 
 
Phosphate monoesters 
Oligonucleotides, Phosphodiesters 
Phosphatidic acids 
 
 ßGalactosides 
Acetylhexosaminides, heparin sulfate 
 ßGalactosides 
Glycogen 
aMannosides 
Sialic acid derivatives 
 
Mucopolysaccharides, bacterial cell wall